Strange (un)fading effect on guitar finnish

[gtr475]

I noticed a kind of strange thing today changing the pots on my warmoth strat. When I lifted the pickguard I noticed that the finish under the pickguard was lighter than the exposed area outside. This means that the finish has darkened quiet a bit.
I thought that guitar finishes faded to lighter colors when the guitar ages. Not the other way around. Does warmoth finishes darken with age? Anybody else seen this happen?

 

[stratamania]

Some types of finishes can darken with age. 

Some of the creams and so forth on older guitars were originally white. I would say the question is not just to do with Warmoths, but a finish can darken with age over time due to sunlight, smoke, pollutants in the air etc.

 

[gtr475]

I hope it is because of sunlight rather than smoke and pollutants. Because it mostly stays at home.