Updated from 12:23 p.m. EDT

Apple's

(AAPL) - Get Report

sweet earnings report left a bad taste in the mouths of some analysts and investors, sending the company's shares lower on Thursday.

Apple's shares were recently off $3.39, or 8.3%, to $37.65.

On Wednesday afternoon, the computer and electronics maker topped Wall Street's earnings estimates by 10 cents a share and offered better-than-expected guidance for its current quarter.

Despite the blowout numbers, some analysts still found room to quibble. On a conference call after the earnings release Wednesday, Apple CFO Peter Oppenheimer warned that the company's revenue growth -- which hit a 70% year-over-year rate in the quarter -- will likely slow to closer to 15%.

Oppenheimer didn't predict how soon Apple's revenue growth will reach that rate, but in a report issued Thursday, American Technology Research analyst Shaw Wu warns that the slowdown could happen as soon as the company's next fiscal year. That possibility is in stark contrast with investors' expectations, Wu says.

Adding to Wu's concern: the average sales price of the company's Macintosh computers and iPod digital music players dropped significantly in its second quarter compared with its first quarter. Apple introduced bargain-priced products in each of those segments in the quarter that are probably cutting into sales of its premium products, warns Wu, whose firm does not do investment banking.

"We are growing more concerned with slowing top-line growth," says Wu, downgrading Apple's shares to a hold from a buy. "In our view, investors do not believe AAPL's guidance and have much higher unpublished expectations."

Of course, any nitpicking with Apple occurs in the context of the tremendous run in its stock. Even after trading down on Thursday, Apple's shares are up 21% in the year to date after more than tripling last year.

That rise has led some investors and analysts to argue that the company is overvalued. The company is trading at 43 times its trailing 12-month earnings, which is well-above that of a hardware maker like

Dell

(DELL) - Get Report

.

On a forward looking basis, the company is valued at about 35 times its projected earnings for this fiscal year and 29 times its projected profits for its next fiscal year. Those multiples will likely come down as analysts ratchet up their estimates following the company's report.

Goldman Sachs analyst David Bailey had little but praise for Apple's quarter. He nevertheless maintains his in-line rating on the stock, worrying that investors might misread Apple's comments on its inventory.

At the end of its second quarter, Apple had four to six weeks of iPod inventory in its distribution channel, Bailey notes. But company officials were unclear about how much inventory they had going into the quarter. That probably led some investors to conclude that much of the gain in iPod sales in the quarter over the first quarter had to do with inventory build, Bailey says. Bailey disagrees with that conclusion, arguing that the bulk of Apple's iPod growth likely came from real sales, rather than channel fill.

Still, "confusion about

Apple's iPod inventory build, and the inevitable approach of harder comparisons, will probably put pressure on the stock temporarily," says Bailey, whose firm has done investment banking for Apple in the last year.

And those weren't the only worms that analysts found in Apple's report. The company's third-quarter guidance -- while above the Street's estimates -- implies that sales will be flat compared with the second quarter and earnings will decline, several analysts noted on the conference call on Wednesday. Some also observed that Apple's share count ballooned 13% in the quarter, diluting earnings.

The expanded share count had to do with stock options exercises in the quarter, Oppenheimer explained on the call. In terms of the company's guidance, it reflects Apple's normal seasonality and still would represent a 61% growth rate over the year-ago quarter, he said.

"We're very pleased with the results of our first half of our fiscal year," he said. Apple is looking forward to the second half, he added.

Oppenheimer had a lot to be pleased with in the second quarter, as Apple's earnings were six times greater than they were in the year-ago period. In the just-completed quarter, Apple earned $290 million, or 34 cents a share, which was up from $46 million, or 6 cents a share, in the year-ago period.

The company's sales jumped 70% to $3.24 billion.

Those results were well ahead of both analysts' expectations and the company's own guidance.

The consensus on the Street was for 24 cents a share in earnings on $3.21 billion in sales, according to Thomson First Call. Apple predicted in January that it would earn 20 cents a share in the just-completed quarter, on $2.9 billion in sales.

Apple predicted that its good times will continue in its fiscal third quarter. It forecast earnings of 28 cents a share on $3.25 billion in sales. In contrast, analysts had forecast a profit of 24 cents a share on $3.21 billion in sales.

In the third quarter last year, Apple earned $61 million, or about 8 cents a share, on $2.01 billion in sales.

That the quarter may be flat sequentially has to do with the company's normal seasonality and with a pickup in lower-priced computers for the education market, Oppenheimer said.

Also playing into the company's projected third-quarter results are recent price reductions on the company's popular iPod digital music players, he said. Factoring into the projected decline in earnings, the company expects to see an increase in operating expenses, partially due to costs associated with developing the next version of its operating system, he said.

The company's recent growth rate has been far faster than it expected, Oppenheimer said. "We don't think our revenue will continue to grow at these levels forever," he said.

For the full year, analysts are looking for $1.11 in per-share earnings on sales of $13.34 billion. Apple did not provide full-year guidance.

Apple's results were fueled by jumps in sales of both computers and iPod digital musical players. The company sold 5.3 million iPods in the quarter, generating $1.01 billion in sales, compared with 807,000 iPods for $264 million in sales in the year-ago quarter.

On a unit basis, the sales also topped Apple's first quarter, which covers the holiday period. In that quarter, the company sold 4.6 million iPods, worth $1.2 billion. The total revenue generated likely declined, because Apple introduced a discount-priced, flash-based digital music player in the quarter.

The company sold 1.1 million of its Macintosh computers in its second quarter, for $1.49 billion in sales. That compared favorably with the year-ago period, when the company sold 749,000 computers worth $1.16 billion.

But stock options did skew some of Apple's results in the quarter. The growth in earnings per share trailed significantly behind overall earnings growth because of the added shares.

Meanwhile, the company ended the quarter with $7.06 billion in cash and short-term investments, which was up $609 million from the end of the first quarter. While much of that gain was the result of the company's operations, some $287 million of it -- or 47% -- came from stock options exercises and the tax benefit associated with them, Oppenheimer said.