Has anybody had this happen? Behind the clear plastic face of the gauges is an "eyebrow" that follows the contour of the dash pad. It's starting to turn white. The original color is gray. Also on damp day's(no rain) the inside of the windshield has moisture on it. Never had this with any of my cars, not even with my 83 Monte Carlo, which I still have. No water leaks can be found. Is the HHR a hot house?
Thanks

 

Sounds like a leak somewhere.

 

You most likely have a water leak somewhere and the moisture collects on the glass as it evaporates from it's hiding place. Check under the carpet at all 4 seats.Usually puddles at the lowest spot. Also check spare tire well.
Moisture is also attracted to the plastic gauge cover and can discolor it or the surrounding colored plastic.