The President's loose jaw problem

While watching the President announcing his choice for the supreme court, I notice something. Everytime he opened his mouth to speak he would move his lower jaw side to side as though trying to line it back up with the upper jaw. What causes this? TMJ or is Roves hands trembling a bit too much these days? I'm serious though I did notice this, anyone else notice it?

Just a nervous mannerism.

It's not uncommon in old coke heads.

LOL Maybe thats what it is. I had noticed it before in other speeches but not as bad as the one I mentioned. Everytime he opened his mouth he pushed the lower jaw back and forth before speaking a word. He seems to be having a tough time here of late with his nerves.