While there was certainly a lot to like, some analysts spotted signs of trouble. (Getty Images)

Alphabet Inc (Nasdaq: GOOG, GOOGL) drifted above $1,000 per share late Thursday afternoon, up more than 2 percent in after-market trading, after the company reported third-quarter earnings and revenue that beat Wall Street expectations.

While there was certainly a lot to like from Google's quarter, analysts were troubled by rising costs and see an increasingly difficult regulatory environment for the company.

Alphabet reported third-quarter earnings per Class A share of $9.57 on revenue of $27.7 billion. Both numbers topped consensus analyst estimates of $8.33 and $27.2 billion, respectively.

In addition, Alphabet reported a 21 percent decline in cost per click and a 47 percent increase in aggregate paid clicks, two key digital advertising metrics.

While most of Alphabet's numbers were rosy, traffic acquisition costs of $5.50 billion were higher than consensus expectations of $5.24 billion.

"I was a little concerned about the [traffic acquisition cost] numbers, but I think that's not too awfully bad. They've been trending up," Nancy Tengler, chief investment officer for Heartland Financial, said on CNBC.

Tengler has been bullish on Alphabet stock, but she says it wouldn't be a bad time for investors to take some profits and trim their positions given the difficult regulatory environment Alphabet will be facing. Alphabet and rival Facebook (FB) have faced increasing scrutiny related to data collection and privacy policies.

TIAA Global Asset Management managing director Stephanie Link says Google's rising traffic acquisition costs are a concern, but its revenue growth confirms that the company is getting bang for its buck.

"They're spending a lot on mobile, they're spending a lot trying to grow in other areas," Link says. "Clearly they just did 22 percent total revenue growth … but the TAC number to me is a little bit high."

Earlier this week, Deutsche Bank analyst Lloyd Walmsley says Google has worked to ease advertisers' fears related to unseemly content on its YouTube platform. "On the back of these efforts, we believe that brands will continue to get more comfortable advertising on YouTube again and we see YouTube as one of the key beneficiaries of the ongoing transition to digital," Walmsley says.