I have had similar (not exact) dreams about being back to school (I got my masters more than 10 years ago), in past 5 or 6 years (at least 3-4 times a year). In these dreams, I see myself going to a classroom or exam session, not knowing my schedule, feeling I have lost time, worried about what I'm going to do. The feeling bothers me during the dream and a little while after I wake up. Feels like I have lost an opportunity, lost time.