In my case, the "red flashing upon door open" happens in only one context:
Nero has finished, given the "success" message about the burn, but I haven't closed the dialog. At this state, Nero must still have some command active in the drive, but not one for writing. At this stage, Explorer can't show a directory, so the operating system doesn't have general access to the drive. It is in this condition that I get the "red flashing" upon eject.
If I close Nero, however, the drive doesn't flash red upon eject.
This seems harmless to me. I don't think there's actual writing going on; it appears to be a "drive state" thing happening. Nero hasn't quite let go.