Issue with locking car

I had the strangest problem today. I drove the car for 5 mins and came back home to collect my wallet. Got out of the car and closed the door (engine still running) with the keys still in the ignition. Came back after 30 seconds the car had locked. Couldn't get in at all and had to call a locksmith to open the door so I could get to the car. (no 2nd when I bought the car)

Has this happened to anyone before ? Do you know what could it be?

No the DIS didn't show the door opened (it works though when you open the door and leave it open). I have an other issue which might be related or might not. The rear demister does not work (fuse checked and so is the relay) and the rear wiper has a mind of its own (more often than not does not work though)