"I Was Bad"

When I picked up Collin yesterday from school, I asked how his day was at school and what he did. He usually tells me that he sang songs or which friends he played with. I was surprised when he told me something different. He said that he had to sit in the "time out chair". I said "oh really" and asked why he had to sit in the chair. He said "I was bad" but could not tell me why he was bad. Based on conversations with the teacher, Collin did have to sit in the time out chair several times when he first started going to school but I had not heard that he had to recently. Could be because he is tired since he is getting up several times at night. He is also sleeping on the way to school in the mornings which he typically does not do.