Is it normal to have sex dreams after a break up?

Here's some background: I've been dating this guy ever since high school and well into college, and we broke up very recently on relatively good terms. We did have a sexual relationship, and thats where a lot of our problems were.

My dreams aren't anything in specific... some include my ex, some dont (some even have people I do not particularly like). Some have sex in it more than once, some dont. Some of the dreams even involve fetishes I dont partake in. Even though the topics are scattered, every time I fall asleep I dream about sex (even when I nap between classes)...

It is all so odd to me