He looks at the date and lets out a very well thought out: "Huh." Welp, seems this situation is more effed up than he realized.

"Maybe she didn't want you to worry about things. Or maybe it wasn't a big deal to her." Or maybe it's been six goddamn years you've been stuck here and your sister thinks you've gone missing.

There's really no way to undo what he's said, but at least he has the luxury of her not remembering next loop.