I sympathise with the original poster but agree with the post above entirely.

I was also questioned about my age on board an SQ flight LHRSIN.

The lovely flight attendant asked me what age I was for alcohol and said (I think I was 17), 17. She said something like "Oh I'm sorry, I cannot serve alcohol until you're 18!" I said "I'm 18 in 6 months". She said, "6 minutes? Oh I'll come back then!"

I got my red wine which wasn't great.