For some reason does my volume rocker misbehave. It works fine for a while, but at some point it won't turn up the volume anymore, only down, so the iPad ends up being muted. The volume icon still shows in the center of the screen when pressing the up button, but had no effect. This has occurred multiple times with restarts in-between. Has anyone else come across this issue? Might it be an iOS fault, or a broken volume button? iPad 2 4.3.1.