Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of Sprouts Farmers Market (NASDAQ:SFM) closed Friday down about 10% after the organic grocery chain reported weaker-than-expected first-quarter results.

So what: Quarterly revenue grew 19% year over year to $857.5 million, driven both by strong performance in new locations (including 10 opened during the quarter) and 4.8% comparable-store sales growth. Adjusted earnings before interest, taxes, depreciation and amortization rose 9% to $84.3 million, which translated to 9% growth in adjusted net income to $38.6 million, or $0.25 per diluted share. However, analysts were expecting higher earnings of $0.26 per share on sales of $862.5 million.

Sprouts CEO Doug Sanders noted his company achieved this growth "despite a difficult produce season, resulting in 32 consecutive quarters of positive comparable store sales growth."

Now what: For the current quarter, Sprouts expects comparable-store sales growth of 5.5% to 6.5%. And for the full year 2015, Sprouts predicts net sales growth of 20% to 22%, helped by the openings of 27 total new stores and comps growth of 6% to 7%. Sprouts also anticipates 2015 adjusted net income to grow 18% to 22%, good for adjusted earnings per diluted share of $0.84 to $0.87. Unfortunately, analysts were more optimistic in their models, which called for 2015 revenue to grow 22.1%, and adjusted earnings of $0.88 per share.

That's not to say Sprouts' performance was as dismal as the market reaction implies. The miss was modest, and it's impressive the company continued its streak of growth in both locations and comparable-store sales. But with shares currently trading at a rich 39 times trailing-12-month earnings, and 25 times next year's estimates even after the drop, I can't blame the market for taking a step back from Sprouts stock today.