My pup still goes crazy every now and then when I crate him. It generally seems that he only does it when he knows I'm supposed to be home (like if I have to go to the store after work). When I first started crating him and he went absolutely nuts I also was worried that he'd hurt himself. He never did. He broke the crate though.
Honestly, I'd say it's because you were there. If I put my pup in the crate while I'm home he goes nuts as well. He's used to it while I'm at work but if I'm home and he can see me he goes crazy (if the door is locked). Alot of times, if I just leave the door open, he'll go in the crate on his own and lay down.