P10: Car stays "on" even when key is out

This pretty much happens whenever the car wants to. I'll take the key out and proceed to exit the car, but then I notice the handbrake light is on, and when I close the door behind me the automatic seatbelts move back.
It doesn't really cause any problems from what I can see...(unless someone knows otherwise) But maybe if left alone for awhile the battery might die or something.
Has anyone had the same problem? Thanks