Recurring dreams about failing?

Recently I failed a board review in college to move on in my major. I found out on March 4th but it wasn't until a few days ago I dreamt I was doing the review a second time (i have another chance in September) and I didn't have anything new done. The second dream happened last night and I only had my worst pieces that I showed the first time, and i couldn't leave to get the rest. Does anyone know why these dreams keep happening? It's not something I think about often when I'm awake; I'm trying to take a break right now and catch up on school.