Casey’s General Stores (NASDAQ:CASY) reported fiscal fourth-quarter earnings earlier this week  and followed up with the conference call. The company earned 60 cents a share for the quarter, which was equal to the previous year and 7 cents per share short of expectations. If you just look at that number, which many investors did, the report looks negative. But if you dig a little deeper, there were important positive aspects, including positive guidance for fiscal 2013.

Let’s start with the past quarter’s shortfall, which was primarily due to two factors. First, lower gasoline margins cost the company 12 cents a share compared to a year ago. Gasoline margins are volatile, so they are a bit hard to predict from quarter to quarter. In this latest report, the average margin on a gallon of gasoline was 13.7 cents, down from an abnormally high 16 cents last year.

In addition, the company had a non-cash adjustment related to self-insurance of 4 cents to 5 cents a share. Here’s an important point: Most companies would have called this out as a non-recurring item, which would have made the miss only 2 cents to 3 cents on an adjusted basis. But Casey’s management, which is long-term and conservative in nature, did not separate it out but counted it against earnings. It’s too bad more companies don’t have the same degree of integrity, and it’s one reason I continue to like the stock.

I was most interested in revenue growth, and the story here is intact. The company expects to grow their store base 4% to 6% in fiscal 2013, and they are projecting a 6.2% gain in food and merchandise same-store sales, and an 11% increase in prepared food and fountain sales. Management is also expecting slightly higher margins in both segments. The company is also anticipating that gasoline volumes will increase 1%, although margins will decline to 14 cents  from 15 cents.

Current analysts’ estimates for fiscal 2013 are $3.54 a share, which would be 16.5% growth from $3.04 in the just-completed year. After crunching some numbers with the latest results and guidance, I think it is possible — but not a given yet — that $3.54 will be slightly high.

I still expect $3.45 to $3.50, however, and double-digit earnings growth should continue well into the future. The company has plenty of room to expand their store base in rural America, and 20% of its stores are currently open 24 hours a day.

While the recent sell-off is clearly disappointing, it has all the makings of a short-term overreaction and, in turn, a good buying opportunity for longer-term profits.