Several years ago I put a small icon of the Theotokos in my car. It stayed there all the time for several years. Over time I began to notice that it had lost its brilliancy of colors and now has a slightly white-washed look. I'm guessing this is all from the sun.
I have other icons inside my room, which are exposed, though to a lesser degree, to sunlight coming through my window. Should I be concerned about these icons fading in color over the years as well?