The only thing that pops out at me that I do that could be considered an OCD is I always have to check and recheck and check again that the door is locked when I leave. I especially am bad about it when I am watching someone elses pet when they are on vacation - I always am checking and rechecking that the door is locked. If my DH is with me I will always ask him after we drove away "was the door locked, was it shut all the way, etc." When I watched my sister's cats I started taking a picture of the door with my phone since you can see that the deadbolt was locked. With my house you can't really see the deadbolt but thankfully my dh is usually home after I leave for work so I don't have to worry about being the one shutting and locking the door. I have been known to drive away and then have to turn back around to make sure the door is shut and locked - it use to make me late for work all the time when my dh had different hours.
Another little quirk I have is that I don't like to leave the dryer on when no one is home. That has made for some stinky clothes if I forget to restart the dryer when I get home and it sits for too long. I wouldn't really call that an OCD though - the other with me and the front door being shut and locked seems to me like an OCD since I tend to have an anxious, uneasy, can't think about anything else feeling until I am sure the door is shut and locked even after checking it again and again I am still unsure whether it is really shut and locked.