I am going to say that its fine. If the rips aren't too big, I can't see it being a problem. Just make sure that the pad doesn't 'shed' bits of foam, and make sure that when you wash the pad that you get all the product out between the cracks.
I think it may depend on your polisher type: If its a rotary -- Not really a big deal imho. If its DA, you may get some reduced performance because of the pad material beginning to 'flex' at the rip point.