de Buyer pan not flat

I received a de Buyer mineral B pan for a gift the first week of August. I haven't used it tons because I've been playing around with it's seasoning and learning more about this pan. (I currently own stainless steel pans and some cast iron, but this was my first pan like this.) Anyways, I have a glass top electric stove, and noticed that the pan doesn't sit flat on the stove. It's quite wobbly actually. Why would this have happened? Did I do something wrong? Or is it an error with the pan? Any thoughts would be appreciated. Thanks! ;) -Lisa