As you stated, it was by accident and not design that you were in with an AD and it turned out ok. They usually enjoy outing people, after all, it is their job to spot reps from gens. Other than the "open 4" and fonts on certain models,there isn't too much that would have given you away to the naked eye. You were fortunate that under seemingly close perusal nothing came of the encounter. It isn't easy to spot on someone's wrist, especially as it is moving. The peril is not just that you as an individual may have been exposed or embarassed, but rather in admiring your watch, AD's take notice at exactly how good reps have become, thus adding fuel to their efforts to restrict or curtail the trade, thus affecting many others.