do you know approx how old he is? Sometimes they go off feed during shed and get grumpy. Also odds are he is a WC or "farm bred" animal so he may take a little time to calm down and adjust to his new environment. What are the dimensions of your cage, is it glass, plastic, top opening, front opening, how is it being heated, are you providing UV, do you dust the food with calcium powder, are you still using aspen bedding, what is your humidity at, etc?