The Chief nods again. Wash doesn't relax well and he knows. Because, in that way at least, Wash is like him. That's why he feels like he needs to look out for him, because he knows Wash isn't looking out for himself very well.

"I met him here. We've been on the same side of an ambush a couple of times now."

He's not sure if "drill sergeant dad" is a reference or if it's just an unfamiliar turn of phrase, but either way he's not getting exactly what York means by it. So, he just doesn't acknowledge it.