In Antonin's time at home, Severus Snape will have had a million other more pressing things to see to than his old comrade's mental health. It isn't a surprise he didn't notice, or ignored it if he did. Here, however, is another story.

"Have you considered starting with getting treatment for the damage?"

He asks quietly, and doesn't look at Antonin meanwhile, instead choosing to pick up that aforementioned tin and go about procuring another joint. He doesn't avoid looking at him because he's embarrassed - rather, he doesn't want Antonin to have to deal with being observed in the wake of a question like that, or have reason to worry about the risks that come with looking Severus in the eyes.

He's fine with the risk of Antonin punching him for asking, though.