By now, Starbucks (NASDAQ:SBUX) shareholders are used to this drill: same-store sales come in within the company's guidance but don't exceed it, and some investors flip out a little, sending the stock down by a small percentage. Today is no different, with Starbucks reporting June same-store sales figures last night after market close. At one point, the stock had dipped about 2% (although it has since begun to recover itself). However, in recent history Starbucks investors have been slogging through with what may seem to some like a troubling period of malaise.

Yesterday evening, Starbucks said that same-store sales in June increased 7%, at the high end of its ongoing long-term guidance, which has directed investors to expect consistent same-store sales figures in the 3-7% range. Of course, for several years running, Starbucks routinely exceeded those figures . by a long double espresso shot. June sales increased 20% to $620 million.

Of course, Starbuck's historic routine of overperformance has resulted in very high expectations for this stock, especially given its premium price tag. There's nothing like high expectations to sour perfectly decent reports, and that has been a bit of a drag on Starbucks for quite some time, especially when you reflect on today's price compared to the highs it saw last winter, when it soared as high as $64. More recently, since the beginning of June, Starbucks shares have lost about 10%.

As someone who owns shares of Starbucks and has every intention of staying in for the long term, a 7% increase in same-store sales doesn't worry me. Especially considering that these most current same-store sales figures were up against same-store sales last June of an impressive 10%. Time travel back to June 2003, and same-store sales increased 10% that year, as well. Not many companies can pull off such consistently impressive same-store sales figures for several years running -- there are no "easy comparisons" here. However, some analysts had higher expectations for Starbucks' same-store sales in June, which helped paint a more dour picture than some of us probably feel is warranted.

As much as the prospect of slowing growth in premium-valued stocks is a perfectly legitimate concern, Starbucks continues to open new stores (including international expansion in key markets), expand its food offerings (such as hot lunch and breakfast offerings), and try to give a little more padding to sales with its music program (you may already know the company nabbed an exclusive Bob Dylan album to go with folks' coffee).

It seems to me that days like today are not only historically a bit obsolete, but a good lesson for investors who are in it for the long term. It can be tough to stand strong when a stock you own seems to be suffering from a continuing slump -- and the psychology behind the market's reaction to same-store sales figures can be a bit baffling, to say the least. However, when it comes to the market's knee-jerk reactions to things like "disappointing" same-store sales that haven't even come in below a company's guidance, it's a good rule of thumb not to sweat the small stuff.

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Alyce Lomax owns shares of Starbucks. The Motley Fool has an ironclad disclosure policy.