Investors in teen apparel retailer Aeropostale (NYSE:ARO) have, in recent months and quarters, been served an unwelcome slice of reality as the company has, perhaps unsurprisingly, failed to match eye-popping past monthly same-store sales comparisons. Hot profit growth has eased that pain. But a closer look at some balance sheet trends nevertheless raises questions about management's ability to pull off its plans to keep the growth coming.

Aeropostale last night announced Q4 and full-year financial results that watchers of the New York-based company -- which competes with The Gap (NYSE:GPS), Abercrombie & Fitch (NYSE:ANF), and American Eagle (NASDAQ:AEOS) -- have grown accustomed to: Margins improved year over year right down the income statement line, which when combined with better than 31% sales growth and "comps" that rose nearly 9% led to about a 55% year-over-year boost in net income.

Yum, right? Yum. Less tasty, however, is some info on the balance sheet. While the company is growing, debt-free, and cash-flow positive, the Flow Ratio turns up some troubling history. A measure of how tightly a company measures its working capital, any number under 1.0 indicates that money comes in more quickly than it comes out. When a company grows quickly, as Aeropostale has, this figure can provide color as you evaluate the quality of the growth.

In Aeropostale's case, the number is moving in the wrong direction: Last year represented the third consecutive year that Aeropostale's "Flowie" actually increased, reaching 1.78 in 2004. It was near or around 1 for the previous five years, which has to raise some eyebrows. Having reached nearly 600 stores -- it will cross that line this year -- Aeropostale is now looking to new concepts (look for Jimmy'Z) in selected locations near you to pump growth.

This disconnect between Aeropostale's income statement numbers and some figures on its balance sheet might go part of the way toward explaining why its shares, while outperforming the S&P 500 over the last 12 months, haven't kept pace with -- for example -- competitor American Eagle and its substantially larger market capitalization even as it nears the latter's store count figure.

Fool contributor Dave Marino-Nachison doesn't own any of the companies mentioned.