I purchased a 03 200 exc about two months ago. so far i have 3 races and 3 playrides on the bike. (250 miles on fairly rough terrain). The forks have slowly become more harsh on the small square edge bumps. what is causing this?? I have not touched the suspension settings. i thought that the springs might be sagging and causing the forks to ride farther into the stroke. or maybe i just need to replace the fork oil, any suggestions?