Sounds plausible to me. Total headcount adds up, good to go. If your friend wasn't being obnoxious or looking out of place, why would they think twice about it?
If you're talking about the new security dictum that pax must not change cabins--I believe that's only for flights into the USA, but maybe AA would have to do it anyway as an American carrier. Besides, there's no security value in that--maybe the crew knew that too
