My cage has a towel tent in one corner and a large oatmeal container tunnel. The guinea pigs occasionally nibble the towel, and shred the inside of the oatmeal tunnel. Are these possible hazards? I wasn't worried about the cardboard, as it's a suggested toy on the C&C site, but my dad is in here every day nagging about it. So I'd like to have some feedback on the cardboard, so I can shut him up, lol!