Am I losing my head at the age of 14?

I could have sworn my friend wasn't in my maths cl, and then immediately after my maths cl, I entered where the other Maths cl was on ( I had to go there) and thought I saw him. He says he was in my maths cl. I think hes lying because if he was in that maths cl, he was demoted to the 'stupid' cl. I don't know if he's lying or I'm seeing stuff!