rear door lock ghost

so, i go to the truck in the morning, unlock the door, put my tools in the rear area, and lock it back up; even check the handle to make sure it's locked.
i drive to the shop up a gravel road and go to pull up on the rear door handle and notice the lock is turned and the door opens without the key.
has anyone had this happen before? seems like there is a ghost unlocking the rear door as i drive up this road. any way to stop this from happening?
cheers,

You say Ghost's ?

yes, that happened on mine. The over-centre spring that is supposed to keep the inside locking lever up or down is broken, so that the lever drops with vibration etc, even though it weighs nothing. Also mine would sometimes unlock if you just kept banging the handle up. The spring is inside the mechanism and inaccessible. So you need a whole new unit, or, I made a spring out of a hair grip donated from shmbo which is fitted outside the lock but behind the door card. It mostly works. It's easy to take the catch mechanism off to fit it.

I've got an elastic band round the handle on the inside, then hooked over a hair clip which is wedged between the door and the glass (If that makes sense), basically just keeps the handle up, but still allows you to open with the key, been like that 12 months and I've never had a problem with it.

i can post you a handle for a fiver....
pm me if you like

mine does it to, i just reverse up to a wall when i park up. not like car crime exists round ere.