I recently got a beardy for christmas. I feed him everyday and give him plenty of water. recently I even moved him into a larger tank. But one thing that I'm not so sure about is he will open his mouth at anyone who gets too close to his cage, I can't hear any noise for him when he does it. He has been doing this for several months now (even before his new tank) but is now doing it more often and for longer. What does it mean?