Maybe not while people are upset, or confused. [Concession, about the people around them, and faintest suggestion of explanation, about Sans's current demeanor. Suggestion, not suspicion, because he's feeling sympathetic. Why wouldn't Sans be on-edge and suspicious, alone in a weird world like this without Papyrus around boosting his spirits, after all!

Papyrus, of course, has had Papyrus to boost his own spirits the whole time. So it's fine and completely different.]

Probably no point asking around about Undyne... She wouldn't be quiet or crying. [And, of course, because she's on vacation. But if she weren't... If that fantasy hope of an idea had any merit...]

If she was here, she'd be running off wherever this attack is supposed to be coming from. [Voice fond and wistful, expression more bittersweet than he usually tries to let on.]