Don't remember my 30th birthday, I had a brand new baby to take care of at the time.
Don't remember my 40th birthday either. No particular reason, I just stopped caring about my birthday. I think I had to work that day, probably FAXed back the HMDA and CRA verification reports.
However, the other day, (and I don't know if the gal was just humoring me or what...), but I had a 6 pack of beer in my grocery order and the checker asked to see my ID! Now I KNOW that I could never be mistaken for being under 21, but I guess it meant that she was in doubt if I was over 30. (The sign says they card anyone under the age of 30.) Good enough for me!