I repaired a few spots on my ranger boat, with the factory gelcoat (perfect white) and the sanded spots have a yellow tint to them. It's not the color because the spots that I filled are white just a little darker white than the rest of the boat (must be due to oxidation), but the surrounding area that I sanded seems discolored. Could it be some thing with the rubbing compound? I'm using Malco Rejuvenatory after sanding with 220, 400, 600, 1000, and then 2000. The repairs look good except a discolored square that I had taped off. Any ideas to what could be causing this?