I Am Having Wet Dreams About 8-10 Times A Year.

I am having wet dreams about 8-10 times a year. I had a vasectomy on May 1, 2009. Thinking back, I believe the wet dreams started not too long afterwards. Can sperm build-up cause my body to find a way to release it, even though it can't happen through my penis? I have a regular sex life of 1 to 2x a week with my wife. I have had the wet dreams from both being on my stomach and side. Is it possible I have a problem?