No offense taken, and I didn't mean to offend, either. FAA display images are quite often taken without permission for blogs, wallpaper, and other 'nuisance' uses. Since it's rare for anyone to ever buy images for such uses from FAA artists, I have no problem with letting them have 'em. It takes too much time and effort to police everyone who nicks a pic, so I just feel it's better to choose my battles. I also feel that the FAA watermark is too intrusive, so I don't use it.
I think you've already gotten your answer about backdating watermarks. You can't, but maybe tech support can.