5th wheel popped out of hitch

It was latched and we did pull test. We were actually on vacation. My husband went to go dump. He pulled out of our site drove about A quarter of a mile, two turns waited in line to dump when they person in front if him dumped his black tank all over. My husband decided to go to the other dump site turned left probably went another 1/8 of a mile stopped at the stop signed started turning left solely and watched it popped out. He checked everything and since I am learning to do everything I go through all the stages.

I don't think the pin box makes any contact. This wasn't our first time out. We bought a brand new trailer last year we have been put approximately 20 times