[demian5]

The only things I could think that "over time" would cause this is:
1. Not having a bolt at the bottom of the fender under the cab, or a rusted fender that cant be secured.
2. A bent fender that the door hits when opening and closing.
3. Tires that rub the fenders when turning or going through dips and vibrate the fenders with the tread.
4. Off-roading on washboard roads.
5. Excessive shopping cart bashing at the local mall.