I just had that happen last week-end while practicing my backing skills (a topic for another thread). I was a little sharp on the turn and felt the bed lift a bit, luckily I had the rails from the tonneau cover on the top of the truck side, they got marked up, hit the pin box in almost the exact spot that yours did. Good luck with figuring out your problem, I will be following this thread with great interest. I do have a trail air pin box and I have read they can have there own issues. Sweet rig by the way.