whats up with this dude?

ok so every time in maths class last year, I would go to my locker before next block to get my books and i never knew when i just felt like i needed to go to my locker. then one class this guy comes up to me and asks "at 1.30pm everyday, why do you go to your locker?" and I never knew i went at that specific time but after he told me that I realized that it was true. Why did he tell me this? and how did he know? like im kinda confused and creeped out