Panera Bread (NASDAQ:PNRA) had another impressive month of same-store sales in August, despite Hurricane Katrina and other major distractions to consumers' wallets late in the month. (Many of us have been awaiting an onslaught of Katrina-related excuses from companies, but that's apparently not the case at Panera.)

For the month of August, Panera reported same-store sales up 7.8%, exceeding analysts' anticipated figures. In company-owned stores, same-store sales rose 7.7%, while franchised stores enjoyed a 7.9% rise in same-store sales.

In a similar manner to last month's same-store sales release, Panera shares increased by 5% at one point today. Despite the good news (and the optimism from Panera's last quarterly report), maybe investors ought to wonder if they're simply paying too much for these shares.

Panera shares have increased 55% over the course of a year, although they have retreated from their 52-week high. However, given another day of big stock moves for the breadmaker, it doesn't hurt to remind investors that last spring, Fool Nate Parmelee predicted a slowdown for Panera later this year, yielding better buying opportunities.

After all, this year Panera has enjoyed the benefits of waning consumer interest in the Atkins anti-carb craze. It stands to reason that the company will begin to face more difficult comparisons later on, mirroring Atkins' decreasing hold on the weight-conscious. For example, same-store sales growth in August of last year was a mere 2.4%, an easy comparison. For the next three months, comparisons will get harder, especially in December, when the company faces last year's same-store sales gain of 7.1%.

For now, investors continue to look at Panera's monthly same-store sales figures as good reason to buy, regardless of the stock's current priciness. Panera's got a P/E of 35, approaching that of Starbucks (NASDAQ:SBUX), a company that boasts many more years of solid performance under its belt. Whether Panera will be able to keep up the pace -- and deliver consistent gains to shareholders -- remains to be seen.

Knead to know more about Panera? Join fellow upper-crust investors on our Panera discussion board.

Alyce Lomax owns shares of Starbucks. The Fool has a disclosure policy.