That's what happened with mine -- both times. No rough handling, just normal wear and tear. In fact, I hardly use the stupid thing. I do remember small bits of rubber or plastic falling out from the sun roof and next thing you know, the shade's broken again.
My SA claimed it would be best to replace the entire thing -- shade, tracks, etc --and that's where the $1850 figure came into play. I looked at him like he was nuts and now deal with the broken shade.