Any chance fuel sloshing around on trip and ethanol laced fuel on fuel system components could have changed anything? This is part of the subjective stuff than can be cleared up on the suggested "fact finding" inquiry. I wouldn't open a can of worms, nor be the catalyst that gets this guy coming at you. Just a simple q "what's your idea to fix". Bottom line is that if he does not "go away" the list of "stuff" might become unfathomable.
