I had the fly noise today and discovered the trim around the windshield on the driver's side is torn. There is a metal reinforcement molded into the rubber strip, and it cracked, then completely broke. Now whenever I am going 65 - 70 mph, it buzzes like a giant fly. It doesn't sound like it's coming from the defroster though, it very much sounds like it's coming from the top of the windshield (and it is).
I took some pics of it today, I'll post them and update this with a link.
Link to pics. Scroll to the bottom, there are three pics of the weather strip, two are IIP, the other is FM. It should be obvious what the problem is.