The only thing I can think of is that maybe this is like a baby teething (that urge to chew on things)? She's still young so maybe she'll grow out of it. I have a one year old female who Occasionally chews through her bonding pouches (I once had to perform dental surgery when the threads got caught between her teeth). I figured she was either bored or just playing, or perhaps wanting to get out. One way to make sure she's getting enough to eat is to check and see if food is left in their food bowl. If it's completely empty, then she might be needing/wanting more.