Is It Normal To Feel Guilty About This Years Later?

Once when I was in high school clay pottery class I stuck a large sharp tool inside a clay tower I quickly made. My friend didn't see me put it in there and so I jokingly told him not to crush my tower, which he of course then went to smash with his hand. He ended up having to go to the nurse's office to get it fixed. Am I the only one who still feels guilty about stuff like this? I mean, that was pretty low. I could have probably gone to jail for it in this day and age even though it was just a minor cut. Maybe I just have an over active conscience to still be letting it bother me. Depression and axiety runs in my family so maybe I'm making a bigger deal out of it then it was. I told him I was sorry.