It's hard to know how much to question it. Sans pretty much feels like falling asleep in random places all the time, so he's not sure how to form a frame of reference. Though...Papyrus being in the same sort of mood Sans is in isn't a good thing.

"Well... You've been having a kind of rough time, lately," he says, shrugging his shoulders a little. "I've felt tired like that for about as long as I can remember."

He says it, and then feels like of awkward for doing so. Does he actually need to share that kind of stuff with Papyrus? It feels like such an awkward mixture of knowing someone forever and just getting to know them.