I can honestly say I am not surprised. Its the gym, what do you expect? When there I just try to ignore the blatant Douche-baggery that plagues most climbing gyms, its just a fact of climbing indoors.
I have to say that the wall hogging is by far more frustrating than bag stealing. Correct me if i am wrong, but didn't you accidentally leave your bag there in order for him to have pilfered it from the lost and found?
Either way, glad to hear you got it back.
You did the right thing in confronting the Douche.