i bought a car last week and the original owner had backed into something and got a few deep sratches on the bumper.. i got the touch up paint from the dealership and he also told me to buy sand paper and sand it a bit.. I just sanded the scratches down, but the paint surrounding the scratches started going dull from the sand paper, i tried not to touch it as much as i could but thats impossible when your trying to sand the scratch. how do I get rid of the dullness/hair line scratches on my nice paint from the sandpaper now? im worried!