I don't think the cage biting and biting humans is necessarily related. My Peanut Butter used to bite the cage bars, but never people, until we discovered he has toofie problems and now with monthly dentals he never bites the cage bars. Hazelnut, on the other hand, who never bit the cage bars, started biting fingers when we were trying to do chin rubs, but only once he was an adult. As a baby he let us give him plenty of chin rubs without biting us. I tried gently blowing in his face or very gently pulling on the back of his neck as I had read that is how mummmy piggies discipline their pups. It didn't work, perhaps because he was no longer a pup! In the end we discovered if we asked him "chin rub Hazelnut?" and waited until he lifted his chin it was safe to give him a chin rub. Perhaps if you could narrow down to why the biting is occurring, you could avoid it. Does Sue allow some time for you to hold her at night before she bites you? It could be her way of saying she needs to go toilet Also, putting her back in the cage immediately after she bites you could be reinforcing the behaviour. When Hazelnut used to bite we never put him back in the cage. We would just leave him on the sofa with us.