Maybe he does. Maybe if it were said, he would simply nod, make no comment, and never, ever forget. Maybe it's for the best Sans held his metaphorical tongue.

[I think they're outside.] he says, knowing exactly where they are. Thank goodness that special sense came back when they were far enough away from Adam. What a strange thing to be grateful for--he's grown to like it. It'd be nice if he could do the same with everyone else important. [By the gardens.]