When I walk into my kitchen I never step on the door sill. While there is nothing bad there, it always feels like there are upside down spikes or something that would go thru the foot.
I have a similar behavior. In addition to not stepping on the door sill, if I'm walking down a hallway or something with tiled floor, I do my best to not step on the outline of the tiles, and only step in the center. Luckily, I'm not too obsessive about this, and if it'll make me look crazy if I do these things in public, then I have enough self control to just walk normal and ignore it.
I also do the locking-and-checking thing, but that seems less of a weird/obsessive-compulsive habit and more of a practical behavior. It's smart to check!
Another one I have is that if I see something hanging half-way off of a table or other flat surface, I'll be bothered by it until I'm away from it or until I'm able to slide it fully onto that surface so none of it is hanging off. I also have a ton of other habits like these, but I could never remember them all.
The only normal habit I have is that I crack my knuckles. But then, I also crack my neck, wrists, elbows, ankles, toes, and knees. I don't consider it a bad habit.