I learned that lesson quickly, after I wasn't scored in 2 out of three races in a row. Those results happened not to matter. Of course, I've also been scored in a race when I registered but didn't start. Now I always verify, and have had to have a couple adjusted. Almost all races use cameras, but they aren't the same height off the ground. So number placement that is great for one race may not work for another race, and the officials may not be able to read your number, particularly in a pack. In one of the races where I had mine corrected, the official had me look at the pic's to point myself out. My number was unreadable, as it was fairly high on my back and the camera angle was pretty low that day. Now I try to check that out before I put my number on. This likely isn't your situation for this race, but is just something you should be aware of. Be obsessive about your number, and check the results sheet.
Is it possible that the woman in the pits joined a lap after you did, and then finished ahead in the pack? That's the only thing I can think of... but as has been mentioned: Machts Nicht. You had a great race.