Yes, I think if a rabbit is continuously getting sore hocks then something isn't right. My mini rexes will only get them when they molt and it doesn't actually get to the sore hock point but you can see that there will be a spot without much fur. It isn't bloody or sore yet, I call it sore hocks but it probably isn't to that point yet. I try to be proactive so it doesn't reach that point.
I add in a piece of cardboard, in addition, to their resting pad and that seems to take care of it. Once the new fur is in we are good. One of my mini rexes isn't crazy about her resting pad, she prefers a piece of cardboard.
If it is all of them and they are chewing then I would say mites or fleas or something like Dood mentioned. They should be itchy on more than just their legs though if they have an infestation.
If no bugs then I would make sure they all had something to chew like an apple branch or mulberry branch. Mine love branches to chew.