Yeah, that's at least a familiar conversational gambit. Familiar enough for Papyrus to follow and make an amused sound before he can help it. "I... see. You're going to, instead, say... I told you so."

Since he apparently has, at least twice...? Awful. Exactly the kind of distracted weakness he should never reveal to Sans. If things are really bad, it will just worry him, and if things are only kind of bad, his brother will make fun of him with it. Especially now that... he gave Sans the idea? He grumbles, with the sort of exasperation Sans was aiming for, only to startle a little at the sensation of it. It's so strange, feeling things like that somewhere inside his neck.