Had that happen to me a couple of times. one time came out of my house and my trunk was open. had no idea wat the deal was. second time was at restaurant looked out the window,,, and my trunk was open again, Realised that i had my keys in my back pocket,,, (Both times) was sitting on the keys.. caused the trunk to open. Also one time had the keys in my front pocket,, as a i was cleaning the wheels squating down the car kept on locking and unlocking.
so i guess b carefuul when the keys r in ur pocket guys. will probably solve un wanted trunk openning..