You Bet!
I had the Britains Rorkes Drift Hospital set up in a bay window (like a schmuck) and some of the figures became unglossy on the side facing the sun. The sun causes the overlay (paint) to heat up and cool down, possibly separating the paint from the metal. I guess if you are going for the matte "look", then clear the plants from the sill and set 'em up! Mike