Ever since I got him, this hasn't abated: I've noticed that my cat, Lux's body language is always defensive, except when he forgets himself and starts to enjoy himself and then remembers himself and goes on the defensive again. By this I mean shoulders up and neck tense, ready to move away. He also walks with his tail down just about always, except when he wants food and then it's up. Is anyone else's cat like this? Does my cat really just have an anxiety disorder or something?