Yep, my K-Line bay window caboose almost had the same issue. The one window right next to the unit is all foggy now from the heat. Doesn't take much to melt them.
Luckily a club member warned me about using the smoke unit in TMCC mode. He apparently had a total meltdown with one of his once.
My grandpa also has a G scale Lionel 0-6-0T from the 80's that has a hole melted through the headlight "glass" from the bulb heat.