Trauma recovery. It's still on his mind moments later though he'd said nothing to the words. Matt isn't wrong, after all. And it's a good lead-in to what Frank has to tell him next, something that feels him with apprehension. Not because he wants Matt's sympathy or understanding, afraid he won't get even basic validation - but what if he doesn't even believe him? He knows he can't let it stop him from warning Matt, especially Matt, who's already vulnerable in so many ways here.

"You'd know that already if you ever listened." No, seriously, how are you only now noticing the Dad vibes?? Something clicks when Matt puts on the shades, a mask of sorts even if they aren't devil horns by a longshot. Still, the familiarity helps him breach the subject he's been putting off. "Two weeks ago... something happened to me, Red." This clearly isn't a personal anecdote for entertainment value, it's a PSA. This happened to me and it could happen to you, too.