Different answers to the same question

I had a discussion 3 different times today. (According to my son) I was talking about what time something would happen. Twice I said 2:30. The third time my son said it would happen at 2:30 and I corrected him. I told him it would be 4:00. The correct answer was 4:00. I had no idea we had discussed it earlier or that I told him the incorrect time. Why, if I knew the correct time, would I tell him wrong? And why would I remember everything that happened before and after and only blank out for the "lie"?

Was the event something triggering? Could a part of you not want him there?

Nothing triggering. It was simply what time his father (my husband) would be off work.