Could you be more specific?

- were you travelling AA F, J or Y?

- was it an "appropriate" time in the day for a drink (some AA people can be funny about this IME)?

- are you using your BA Silver (or Gold if you're profile's out of date) or another oneworld partner?

- is there any possibility the agent thought you were too young to drink?

- did you have a connecting intl itinerary?

- which lounge was this?

- were you actually told it was a change in policy?