No I haven't, but then I don't use cardboard holders for Chipcos. I would think the Mylar would be the least likely to show the color as it's pretty slippery and doesn't have plasticizers that get on the chip and accelerate the process.

The point of my post is that what you store them in is not likely to damage the chip. The loss of color pigments will occur anyway; just a matter of whether you see it or not.