Back to school

I keep having this recurring dream that I have to go back to school because I failed some course. Why would it take over ten years for me to realize it? The dream alternates between high school and college. In the college version I have to move back into the dorms. I think it has to do with the fact one of my friends actually had to go back to college because he failed a class ten years ago and finally wanted to get his diploma. He use to call me on his way to class. We would laugh that he was keeping the dream alive. Not sure what dream that was. When I wake up sweating in the middle of the night I am pretty sure it's a nightmare.