Just received a second inspire pro this weekend to add to the fleet. Everything seems good except for one thing I have never noticed on my other Inspire rig. The transmitter after a few min has a audible hum or buzz I have never heard before. Nothing obvious seems loose. if I turn it off and back on it goes away, then returns a few min later. 1) Am I losing the little bit of mind I have left? 2) Do the ALL hum and I have never noticed? 3) Thoughts on returning for a new one? Thanks Gents.