Revell/Monogram decal problem or.....?

I had a problem with decal film yellowing after my first attempt at overcoating with Future and at first thought Future might be the problem.  However, recently I had the same problem again using a completely different clear overcoat and realized that the only thing the two incidents had in common was the fact that in both cases it was a Revell/Monogram kit.  Has anyone out there ever had a similar problem with R/M decals?  Never heard of it, but I'm still stumped as to the cause.

TomB