The thing is, I don't think it'd be that awkward for him. I bet he'd find a way to say, "you know, I got rejected once..." and you'd walk out ready to rock and roll.
I think the most beneficial thing would to be blunt with a person, tell them exactly where you think they have gone wrong. They may disagree but in the end pg is the one with the yc program to offer and gets to make the call, rightly or wrongly in heinsight who makes the cut.
I don't think tiptoeing around it really helps either side.
"Why didn't you pick me for yc?! (sob)"
awkward lunch?