3 out of 5 of my new girls have been sleeping inside the tube that connects the top and bottom bins of their home together. This tube is vertical so they are basically sitting on each others heads to do this. Why? This is the only tube in the cage, they have a bunch of other hides they could also be using. The other 2 are curled together in a plastic igloo looking far more comfortable than the tube girls. Should I add more tubes so they at least aren't stacked together? Also so that the others can get by to go upstairs of they want instead of being blocked by 3 mouse butts?