Now that I am using my Powerbook away from my iCurve, I noticed a really strange sound that no one else has brought up in any threads here. With it on my lap, if I move it so the base is anything but parallel to the floor, it kind of creaks. I can't really identify where the sound is coming from and it doesn't seem to be HD/hinge related at all. Is this bad (it doesn't sound too great) and/or does it need fixing?