my five week old has taken to the litter box quite well after some gentle prodding the first two days i had her. she never misses, always uses it, etc. after she eats, she gets a little burst of energy and goes crazy. sometimes she will go into the litter box and roll around and chew the box and bat around the litter a bit. it's not affecting her use of it but i'm wondering if this is a bad habit that could lead to bad behavior in the future? should i gently take her out or just let her go nuts if it's harmless fun?