Okay, well yesterday I brought my MBP back from school and noticed that when it's running it makes a wierd sort of mechanical crackle... It seems to be coming from the left side, I think maybe the upper left side... If this were any other computer I wouldn't be that worried, but it didn't used to do it before... Also, though it's not really loud it gets a bit annoying sometimes... Does anybody know what it is? Should I be worried?