What? He doesn't know whether he did or not?
People on drugs often don’t know what is going on around them. I was once going to some event and was entering a parking lot at about 5mph behind a hippie type in a jeep when he jerked to a stop, got out of his vehicle and asked me if I hit him (with my car). I said “Look at the distance between our cars now.” which was at least six feet (as close as I’d got to him when he jammed on his brakes), and he then said “Well, I thought you’d tapped me.”, got back into his jeep and drove off.
Definitely a drug-related non-incident in this case.