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What: Shares of BJ's Restaurants (NASDAQ:BJRI) were getting thrown in the trash today, falling as much as 12% after serving up a lukewarm earnings report.

So what: Adjusted earnings per share were even with estimates at $0.27 a share, but GAAP EPS was down to $0.24 from $0.34 a year ago, though $0.06 in profit last year came from the extra week in the BJ's calendar year. Operating margin also decline by about 3 percentage points. Revenue increased 8% to $184.8 million, and same-store sales grew by 3%. BJ's opened five new restaurants, bringing its total count to 130, and plans to add 17 new restaurants in 2013.

Now what: Nothing was particularly bad about BJ's earnings report, considering it hit analyst views, but the drop in EPS and operating margin is disappointing for a stock trading at a P/E of 26 even after today's drop. The market was also probably hoping to see better results than the 8% top-line increase BJ's delivered. Still, this is primarily an expansion play, as BJ's is growing its store count by 13% this year and sees room in the market for as many as 425 restaurants nationwide. If the company can pull off that kind of growth, today's numbers will be just a blip on the radar.

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Fool contributor Jeremy Bowman has no position in any stocks mentioned. The Motley Fool recommends and owns shares of BJ's Restaurants. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.