That's a good question. I guess I was suggesting more investigation in general, for any such similar experience, but in Paul's specific case, there might well not be any investigation he could have done that would have led to a firm conclusion, which means he'd be left with, "I don't know what just happened."
Well, plenty of things can be life-changing but perfectly normal and understood (winning the lottery, for instance). But Paul's experience was other-worldly, given the supposed appearance of someone who had died.
If I see, for instance, Abraham Lincoln (whose appearance I'm very familiar with, from photos), I'm gripping the handrail really tight, looking all around me for what else might be going on that is completely unprecedented, and questioning my sanity, frankly. That would turn my world upside down, whether it was really Abraham Lincoln or not.
Actually, wouldn't one's first thought be, "You're not really Abe, you're an actor or an imposter or are just dressing up, etc." I wonder if Paul thought anything similar. He gives no indication that he did, and that's not to his credit.