Even if he's wary, Minato's concern is real. He doesn't trust Seito one bit but that alone doesn't warrant not caring. No, Minato's seen too much for that, and he got tired of not caring a long time ago. His voice is quiet.

"Do you want me to get you anything?" Water, food...he might have some medicine back at the house. Of course, he's also perfectly willing to give Seito some peace and quiet, if that's what he wants.