Batman cape discoloring?

[Earth 2 Chris]

I noticed two of my fairly minty loose Batmen are starting to have issues with their cape color shifting. Both had a few spots here and there, but this seems to have spread on both, with the blues changing to more purple color in larger areas. One is an early RC Batman, and the other is a UK Palitoy Fist Fighter. My straight-off-the-card 79 Pin-Pin Batman with a dark blue cape has yet to have these problems.

Is this common?

Chris

[skid14]

yep. a lot of the early capes do that. ive also noticed that the later straight arm batgirls keep a real pretty blue cape too as your 79 pin pin.

[Earth 2 Chris]

I've seen early capes like this, but I've never seen them actually change over time.

Thanks for the input!

Chris