I'm not sure if this is a symptom for OCD but:
I remember one time when 2 of our 4 Wiimotes were out of battery. So I went to the store and bought 8 batteries, just in case the other two ran out as well. But when we changed the dead remotes' batteries I felt like I had to put the new batteries on the other two remotes as well. I kept telling them to do that, but of course no one would to wast a couple good batteries. That bugged the shit out of me for a while.
Also, when I was a kid I always made sure that when I go up or down the stairs I'd take the last step with my right leg. Eventually I've memorized how many steps in a stairway from places like my friends house, hospital, school, parks etc.