I get the door ajar issue also but ONLY in the winter time when its really cold out. It tends to mostly happen when I go over bumps. This winter it got to the point that I just pulled out the bulbs in the overhead light so that I didn't look like a complete idiot while driving down the road.
WD-40 didn't do anything for me but I'm going to bookmark this post so I can figure out which door is causing the issue this coming winter.
-- Jess | 
