I noticed this yesterday. It's fogging up all colored like this when my AC is blowing. It clears up when the heat is on or the AC is off. It's still there, you just can't see it as well.
Anyone know what this is?

 

Plastics in all modern cars when they get hot will expel gases that cause a film on glass. A bottle of something called Windex and towels made of paper have been known to clean said glass.