So I guess 'case is closed' now. Well that was an interesting thread. Zzzzz....UPDATE
Dealer couldn’t recreate the problem, scanned it and said they couldn’t find anything wrong at the time. The had it for three days drove it to and from places and couldn’t find issues.
They fixed the tailgate by putting on new studs to secure the tailgate though so all good there. Guess time will tell and we will see if it happens again.