Crochet help - Edges curling in

I am very very new and last night did my first crochet ever work, I did a simple single crochet 25 stitches back and forth for 15 rows. It is really just a test piece although I like to think it could be a nice potholder! Anyway, as this is literally the first thing I have ever crocheted, ever, I am not even sure if my "problem" is one. When I was finished going back and forth, the edges/corners of the square (not an afghan square) curl in like a cannoli tube. I did notice the same "inward curling" while I was working it too. Am I doing something wrong?? I am still a few practice rounds from really starting a "piece" but want to get any "kinks" worked out early!!