Has anybody else found that the bumpers break after a couple of months close to the dock connector? The rubber parts on the front and back seem to be ripping on the inside, that crack then slowly but surely works its way to the outside of the case so that the rubber is completely torn. Mine has started doing this, 2 of my friends with iPhone 4s have also experienced this. Theirs is already unusable. What are your thoughts on getting the bumper replaced? I mean we got them for free, but it's not like there was no reason for giving them out for free Thoughts?