Charlie will go through spells of nesting - he'll only do it for about a week every month or so. He doesn't pull out a lot of hair, it's more of just what he sheds in that week. He grooms himself before I have a chance to and keeps the fur in his favorite box. It's not all over the floor so I usually just leave it alone until we change out his boxes (after he has chewed them to death). The weird thing now is that he has started to use Daisy's fur too! She's got a bit more fur than him and she sheds more - it's kind of ingenious actually. He's not pulling it off of her though, he gets it off of her cage where it builds up beside her litterbox and where she keeps her toys and a little nest of her own. He's done this since I've had him (almost 3 years) and he's happy and healthy, too. I only know what I've learned from having my buns, and I never thought anything of him nesting other than he just wanted a soft place to sit.