I bought this ap1 headlight diffuser in a group by in 2010. This piece was not yellow when it arrived. It has been in a box for < 2 years, and when I took them out to install them, they looked yellow. You cannot see the yellow when looking directly from the top, but you can see a yellow strip when on it's side. It looks like reflective material, but it makes the diffuser look terrible. When in the sunlight, the entire diffuser looks yellow. I've tried cleaning it but it seems it is inside the plastic and cannot be cleaned. Has anyone else experienced this?