Window Tint
I think the window going down slightly would not cause a problem. Anyway, just to be sure you can always ask the experts
I also got my G6 Coupe tinted couple weeks ago, 35% front and back and 30% on the door windows and I never had problems with it. I asked help from www.TintBuyer.com. They provide relevant information about window tints such as its %, quotations, current tint limit every state and will help you find the best professional tinter near your area.
I think the window going down slightly would not cause a problem. Anyway, just to be sure you can always ask the experts