Well, that confirms it. This isn't how he imagined he'd meet Sans again, but... this isn't how he imagined he'd be meeting anyone. Right now, he's more relieved about being up and off the floor.

"Sorry, I couldn't think of any good questions."

But mystery solved anyway. Asriel looks Sans up and down.

"... Wow, so you're really a human now? Are you going to be okay like that?"

Asriel doesn't know what it feels like to go from all bones to all... well, all the stuff that humans are made out of. A change that big has gotta feel pretty weird.