The windshield glass on my 2007 335i coupe has deteriorated during the past year, with specks that brightly reflect sunlight and produce intense glare, especially during morning, and late afternoon when the sun is shining on the front of the car. A close and thorough visual examination of the glass surface fails to reveal any pitting or "sandblasting" at all (although that was the primary diagnosis by the dealership mechanic), and the surface feels completely smooth. Do any members know of BMW windshield glass actually degrading with time, possibly due to it being incorrectly tempered? I think that the windshield replacement should be covered under an extension of the warranty. The dealer price for an OEM replacement is $1655, which seems to be incredibly high - although I realize that the sensor for the car's rain sensing wipers may complicate the installation. Would having the work performed at a windshield replacement shop using OEM glass be a suitable alternative?
I've been using I think it's Safelite for years. Actually almost once every year for the last 3. As long as they use factory trim, you are fine. Some dealers source out windshield repairs to 3rd parties as well. I'd rather have my windshield replaced by a company whose only business is replacing windshields. Can't help you with the deterioration though.
I wouldn't be afraid to have a 3rd party replace your windshield too. Those guys do it all day long and usually have it down to a science. I have seen some issues on E90's when the glass isn't installed correctly. The cowl panel trim under the wiper blades must be able to fit tightly to the windshield to keep water out. If not water will leak inside onto the heater blower fan and cause it to fail.
I read your post the other day as I was just surfing through the forums and it just hit me this morning as I was driving to work. I also own a 07 335i, as I was driving east with the sun in my eyes I noticed the exact same issue that you have described, since I had recently washed the car I knew it was not dirt and I have noticed it before but thought nothing of it. I really have no solution or ideas to pass on to you but perhaps there is something to this. I will check with a dealer here and see if there may be service note or anything.