I had this problem again this morning with my new GT, having had the same trouble with my previous one.
It is not due to any damp in the car overnight. The problem only appears to occcur as soon as the door is opened. The windscreen immediately mists up and then forms a thin layer of ice.
I have tried cleaning the inside of the screen with anti mist solution when I park it overnight but it still mists up in the morning. It is then difficult to clear the thin layer of ice off the inside of the screen.
I would not want to spray it with de-icer inside the car and the ice wont just wipe off, so it has to all be scraped off or I have to wait for the heater to warm up sufficiently to clear it. Unfortunately, unike Ford, Alfa does not seem to offer electric heated windscreens.
Has anyone found a quick way of cleaning off this iced up condensation or preventing it forming?