Got a weird issue with one of my avatars. For some reason when I lift my arms upwards or swing them around the front of my sides heading up, like, my avatar's entire chest area (not breasts, just like the chest and below the neck) "puffs" out? like as if I was puffing my chest out. It's very odd. In blender when I move the arms up or rotate the shoulders up the chest seems to behave normally, but in the actual game I get this weird puffing effect. 

Anyone experienced with this thing have any ideas? I want to fix this it looks really odd