I've noticed when I raise my arms higher than my shoulders, I heard a cracking sort of noise in my joints (i presume its the arm/shoulder joint). It's most apparantly when I'm lowering a lifted weight from above my height (like arnold press). It doesn't hurt, doesn't seem to hinder performance or anything else. It's not getting worse, it's just there. It sounds like the bones are cracking in the joint. Any idea what's happening here?