Hiding blue tang???

Hi everyone, I have a question about my blue tang, I bought him about 2 weeks ago and he is EXTREMELY shy, he never comes out from under his rock except to eat really quickly and then darts back under the rock.... is this normal for these guys? I've had ones before that never did this? Anyway to help him with his shyness so he actually comes out and swims in the tank? I'd like to see my pretty blue guy.

Thanks Jennifer