Sans is very good at not telling people things. Things that he knows, things that he's feeling... Who knows how he actually feels about his snow lumps? Papyrus has this nagging feeling that they're as symbolic of his self worth as Papyrus' excellent sculptures are of his own.

"I don't know how they can stand Hotland. Could stand." Papyrus frowns, confused for a moment. "We did go to the surface. So, why are we here...?"

Well, best not to dwell on it. He can multitask. Think about that while starting to build up a mound for the future car's base.