I had the roof trim issue on my 2008 328i and it was replaced under warranty. On the driver side only. Can't figure out why just the one side. Dealer indicated it was a common problem. No issues with interior trim.
2006 M Roadster Imola Red
2000 M Roadster Imola Red (gone but not forgotten)
1997 Z3 2.8 Roadster Red (gone but not forgotten)
2008 328i Sedan Gold