Wat's Happen?

What's happen to him today? Yesterday still said "Hi" to me when he saw me. Besides this, he was also happy when he get his ESOL exam Certificate. But today when I talked with him, he looked like don't wan to reply me... Reply me with short answer. What's his problem? Teacher punished him? Get scolded? Next week try to ask him again... By the way, I gave him a box of biscuit. Hope that will make him happy...