Here at Fool HQ, it's a particularly warm and muggy day outside, the kind of day when one might be tempted to channel one's youth and go to 7-Eleven (NYSE:SE) for one of its infamous treats, the Slurpee. In lieu of that treat, I'll write about the convenience store chain's same-store sales in May, which (not surprisingly, given recent trends) increased.

7-Eleven said that same-store merchandise sales in May increased 3.4%, with total sales up 5.5% to $1.15 billion. Gasoline sales, an important piece of 7-Eleven that many investors have been keeping a close eye on, increased 7.1% to $414.9 million.

As fellow Fool Nate Parmelee pointed out last month, same-store sales in and of themselves aren't really that much to look at -- their true helpfulness is when one looks at the trend over the course of years. What's known as an "easy comparison" to the year before can make same-store sales look a bit more impressive than perhaps they really are -- in this case, 7-Eleven did have a tough act to follow, what with its 7.8% increase in same-store sales last May, which gives even more credence to the same-store sales increase.

Much has been made of 7-Eleven's gas sales -- and how consumer sticker shock may or may not affect the convenience store chain. Shares of 7-Eleven didn't do much today -- and that's fine. In the long run, long-term investors know that 7-Eleven has posted some pretty impressive quarters recently -- last quarter was a case in point.

Judging by this chart, 7-Eleven has been going like gangbusters for the last year, and it has consistently marched higher over the course of the last several months. It's likely many investors are feeling nervous, about this and the fact that it trades at a forward P/E of 24. However, those who are in 7-Eleven for the long haul -- on the merits of the company's continuing innovation and the possibilities inherent in its technological plans -- can't let themselves sweat the small stuff. It might be time for a Slurpee instead.

For more on 7-Eleven, see the following Foolish content:

Alyce Lomax does not own shares of 7-Eleven.