Anyone dream about masturbating?

This is kind of weird, but I've noticed that I frequently dream about being in the middle of jerking off and then someone comes in and I can't finish. That seems to be my only sex dream. What's weird is that I'm in a relationship and just don't understand why I would dream about that so often. I know dreams may just be random neuron firings, but I do believe they sometimes can mean something more. Can anyone relate?