Ah. Yeah, it's not hard to imagine why that is. Sans understands the caution, honestly, based on everything he's seen...he just hopes that the indirect approach actually works. He settles back, apparently fine with it even if Frisk isn't.

"Gotcha. So you're the middle man, huh?" he asks, ostensibly unaffected by the difference. He pauses for a moment before adding: "Thanks."