My FRST does the same and so does my mates. It's just one of them things. The drivers side shock always tends to become more lazy quicker as its the side that is used the most. If it only rubs on the one side I'm guessing it only scrubs over large bumps at higher speeds. Changing the shock is really the only way to deal with it but really I'd just be more careful when driving and go slower over the larger dips and bumps. Jamie