Stress?

Right now I am feeling stressed and I can not figure out why, even if my life depended on it.  I keep think that maybe it has to do with school, but tomorrow... well today I don't have to much going on.  My English class is a breeze, my tutoring session is helpful, my American Foundations class isn't hard, and i have already taken my Math test (I got a 78% on it and i am happy with that because i am terrible with numbers).  So I'm sitting here wondering why i feel this way and consequently blogging about it.  I have felt this mysterious stressful feeling before, but back in California where i have my sister to talk too.  I don't know whats wrong, but as the day starts I know it will most likely get better.  Everything usually does.