I have watched my bunny to see when he is biting and scratching/digging on things.....
Usually it is ME who he does this to, but sometimes to his "puppy"which is a stuffed animal of his own. He has not bitten INTOhis puppy, just like nips. This is also true of me, butsometimes the nips get a bit hard! lol.
Now, this all leads me to my point. I think that (at leastfor my bunny) it's a sign of "hi there, I love you, this is mine, and Iwant to play with it" .....
It's all about attention and/or I love this or you so much!!!!
Of course, I get that digging and nipping when he wants to be petted, but that's ok too