Why do I always take off one sock in my sleep?

Almost every night, I go to sleep wearing socks (ankle-height, same socks I wore during the day). Almost every night, I take off the right sock in my sleep. I do this by using my left foot to wriggle into the elastic of the sock near the ankle and push it down off my toes.

I know this is a slow process, because occasionally I wake up with the right sock half-off (about halfway down my foot, bunched up). I have NO IDEA why I might do this—no recurring dreams about socks, no sock trauma in a previous life.

Any thoughts? Am I terminally weird, or is this something other people do too?