I'm a door checker. I'll drive around the block to make sure I see that I remembered to close the garage door. I've also driven miles back to my house, apartment, or dorm room (back in the day) to make sure it was locked, and when Mr. LG is out of town I'm up checking the outside door locks a couple times a night. I've also been a OCD alarm clock checker, up several times a night to check to make sure my two clocks (clock radio and battery back up) are both set, but I don't do that anymore unless I have a particular meeting in the morning as I know my daughter won't let anyone sleep in past 6:30 anyway.
This thread makes me feel more normal - cool.