Walgreen's (NYSE:WAG) cheeks may not quite have a rosy glow, but all vital signs pointed toward solid health in its fourth-quarter checkup earlier this week.

The company's 8.8% sales growth may have paced behind top-line growth trends of the recent past, but it remains impressive in light of today's economic environment. Many other top-notch retailers, like Best Buy (NYSE:BBY), are falling short of historical growth rates, while weaker players like Circuit City (NYSE:CC) seem to be on their last legs.

Though comps slipped from previous quarters, they still ran 2.6% higher year over year. In my opinion, positive comps are the first and most important vital sign for any retailer. In addition, the company reported market-share gains against its leading competitors in 58 of its top 60 product categories, according to ACNielsen rankings.

Gross margin slipped 40 basis points year over year. Management admitted on the call that it invested more heavily than usual in promotional activity, but the experiment didn't drive enough traffic to pay for itself. The company will "moderate" its promotional activity in the future. Though this overinvestment amounted to roughly $0.01 to $0.02 per share for the quarter, I don't fault the company for trying to squeeze a few more dollars from unusually tight-fisted consumers.

Expense growth of 5.5%, on nearly 9% higher sales, looks exceptional at first glance. But expenses were actually around 8% greater when you back out an adjustment for vacation accruals. I still think leveraging expenses in the face of gradually slowing sales growth is a solid accomplishment. Walgreen made tighter expense management a top priority nine months ago, and it's following through on that promise.

All this added up to earnings of $443 million, up 11.7 % year over year. Backing out the vacation accrual, the bottom line actually fell by 8%.

Is now a good time to buy Walgreen? Given the market's incredible recent volatility, I understand that Foolish investors may be more focused on what Congress and the Federal Reserve are doing (or not doing, for that matter). And Walgreen remains locked in a battle with CVS Caremark (NYSE:CVS) over who'll acquire Longs Drug (NYSE:LDG), leaving a minor halo of uncertainty over the stock.

Still, Walgreen trades at less than 15 times trailing-12-month earnings, a valuation we haven't seen in more than 10 years. That might be worth a nibble when the credit-market dust settles.

Further Foolishness:

Fool contributor Timothy M. Otte surveys the retail scene from Dallas. He welcomes comments on his articles, but doesn't own shares of any of the companies mentioned in this article. The Fool has a disclosure policy. Best Buy is a Stock Advisor and Inside Value selection and the Fool owns shares of it.