I have the sweetest little cuddlebug rat named Uma, she has 2 other cage mates and they all get along great, Uma loves play time and handling etc. BUT if I try to interact with Uma in the top back corner of their cage, all hell breaks loose and shes biting. No puffing or hissing just hard bites. She doesn't attack her friends, and once she's close to the door or in any other part of the cage she is back to being an amazing little rat. Is this a type of cage aggression? How can I help her? I tried to put a litter tray with waste in it in the corner to stop her from sleeping there, but she just kicked all the waste out and slept in it.