We found this problem with our coach with bathroom door. Found that the strike plate on the door frame was not cleaned out very well when cut out. There was wood debris behind the plate that prevented the "tongue" on the door latch from springing in far enough to stay latched. It felt secure when I pulled on the door but didn't take much coach flex to allow it to open. I took the plate out, cleaned the cavity and even put a small spacer behind the strike plate to bring it out flush with the edge of the frame as it was slightly indented. All this stopped the door from opening on future trips. Just poor construction at the factory was my guess.