He may very well just be a grumpy cham, but theres blogs online that show ways to try to get your cham to warm up to you. For instance, move slowly, try to associate your hand only with food for awhile, don't stare at him too much through the cage, eventually when he grows up he should stop being as afraid of you. Alot of people recommend hand feeding to have them warm up to you, hold some food close to him for as long as it takes for him too get it out of your hand. Do that enough, and he may eventually walk onto your hand and up your arm!