Progress bar drop?

[Kamxam]

I was playing last night, and i noticed that one of my sim's grade progress bar went from about 1/4" from the bar top to about 1/3 full in a few hours. She's an unstable sim and was going through an episode so i was wondering if that would cause it to drop like this? She graduated fine and got a degree, but ended up going from a most likely "A" grade to a "C" grade at the end as i didn't have time to raise it before the final.
Has anyone ever had this happen?

[Shirin]

The progress bar will continually drop throughout the day if the sim is not actively working to raise it (in class, studying, working on associated skills, or playing with the degree "object"). I just had a sim finish a 2 week term, and over the weekend, he went from full bar to about 1/3 less. It will also drop while they're partying, sleeping, showering, etc.