My boy (a panther as well) was in his juvi cage til 8 months. I got him at 6 months and he was bought as a package thru a reputible breeder with his cage, lighting, vits and supps, dripper & everything needed for him.
It was a package that was sold on the internet through their site. After he has settled in a gotten used to us and less stressed it was obvious that he hated his cage and was always looking for a way out. It was way too small for him, he couldnt hide or climb and never was verticle and would just sit on his fake vines and branches and do nothing but be grumpy.
My cham doesnt try to dig but he used to just look at the door and want me to open it (I mean just stare at it) or pace so I would open it and he would scoot down his vine to the floor and make his way to his fiscus in the window by the sun where he has a great view and would dream of all the big trees outside. He would only venture back to his cage for food and water (from his dripper) and was physically put back at 7.30 kicking and screaming for bedtime.
So funny to watch him just to watch him stroll across the lounge room floor to his tree, its like he owns the place. I used to mist him on his tree and he was happy til he got his bigger cage and he settled into it. He still loves to get out but he is more settled and doesnt pace anymore and knows his cage is his home now.
They definatley like their space, to be able to climb and hide when they feel the need.
If your temps are good he maybe just wanting more space and to get out.