He... doesn't, actually. While Childermass can recall the conversations well enough, for the most part, he can't really discern what she might have to apologize for. Overall, anytime she yelled at him or otherwise was uncertain about him (in Portland, anyway; he's not sure if that uncertainty carries over) hasn't ever been too off.

So, he raises an eyebrow, giving Peridot a curious look.

"For... what?"

Why would anyone apologize to him, of all people, anyway?