For what it's worth, I have a refreshed 22 AT4 and had the same problem several times. Within the first 6 months of picking up the truck, I would notice it was open by noticing a "bump" in the back if I hit a rough spot in the road. Well, this was the tailgate bouncing since it was down! I got to where I started checking the tailgate camera now and then. Come to find out, the tailgate button is next to the one that shuts off the auto shut off, which I always select after starting up. I hate that feature but know the white house pushing for better mileage, manufacturers are having to install. Anyway, I was bumping the tailgate button! Since then, I am Very Careful to not touch the tailgate button. I swear just looking at it will drop the gate! LOL All good now though.