Fiver Pin Separated From Hitch on Interstate

Something is amiss here. It just seems unreal that the hitch just "unhitched itelf then locked itself" in one fallswoop. I, along w/ others feel that the OP wasn't hooked up right after the overnight stop. OP didn't say wether or not he dropped trailer then re-hooked it. IMO, it seems almost impossible to have hitch come unhooked by itself UNLESS there was a major part failure. Years ago, I worked for a company driving a semi and was told to use "X" truck and hook up to "X" trailer. Hooked up, did tug test, went to leave BOOM trailer dropped in yard. Mgt blamed me for it as they said others used the same truck w/o incident. Funny tho, week or so later, same truck was in shop getting 5th wheel re-built. In OP's case if things are brand new, then IMO, just wasn't hooked up right as the jaws won't come open if locked w/ padlock, carribeaner clip, etc.