It seems like Changmin had to join reservists training for discharged soldiers which could last a day or 3 days, and sometimes they can stay at home after their exercises or stay at the barracks (read about it here or here)!
He already made a new fan! we hope he do well~^^
OP said he’d bought juice, mini-shell (a snack bar) & Mentos. As he acted friendly as though he was a familiar hyung, from today, OP’ll be a TVXQ fan✌ he was really nice!