If you've been watching Nordstrom's (NYSE:JWN) shares fall by almost 5% since the company reported July's same-store sales last Thursday morning, you might assume that the comps numbers were terrible. Well, just remember what happens when you assume.

Nordstrom's comps for July actually rose 9.4%. So what's the problem? Well, a calendar shift meant that July began and ended a week later this fiscal year, but it also added an extra week to the period. And although that additional week boosted sales, management said it negatively affected the quarter as a whole. The exact impact wasn't quantified, but same-store sales still would have risen 5.9%, which in turn still trounced Wall Street's 4.2% expectation.

Some onlookers also may have been spooked by projections for a comparatively sluggish fourth quarter, which is an important selling period for all retailers. And just to make things more convoluted, the third quarter will see a gain over last year, while Q4 will come in lower. In tandem with that performance, the company expects a 4%-5% increase in same-store sales for the next quarter, and a smaller 2%-3% rise in the following period. But for the year, when all of the calendar shifts are balanced out and their impact is removed, same-store sales should still increase by a solid 5%-6%.

Nordstrom remains the class of the luxury retailers. Its legendary customer service is a competitive advantage that can't be easily duplicated, and the company spends a lot of time, money, and effort training employees to maintain that distinction. For instance, on its website, you can get live help not just from a customer-service representative, but also from a beauty consultant and a designer specialist. While Saks (NYSE:SKS) is improving in this area -- and reporting very good same-store-sales results -- it is not at Nordstrom's level just yet.

At a trailing price-to-earnings ratio of 18, this just may be one stock to grab before the sale is over.

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Fool contributor Larry Rothman is happy to receive feedback, and he promises to read it when he's not being wrestled by his three children. Feel free to email him at [email protected]. He doesn't have any positions in the companies mentioned. The Fool has a disclosure policy.