Of course Tidus is going to pick his head up for a chocobo--he's depressed, not heartless. The sight of the guy even twitches his lips, makes it seem he might be smiling a little. It's not something that sticks.

"Figured I owed you," he says, a trace of humour in an otherwise dull reply. He'd say he likes it up here, but it's more complicated than that. Still never stops him from coming up there to sit in place of his tiny room when he couldn't sleep, as if the open sky gave the illusion of freedom.

So he follows with a "Sorry about that" instead, rubbing at a hand where the two meet off his knees in an embarrassed gesture.