I've always been old fashioned for my age. I grew up listening to classic rock, going to concerts (Rush, The Who, etc). I always dressed nice, got right into corporate work out of college, had a "professional" demeanor. So it's hard to have a "Geez, I'm old" moment that really stands out... but here are a couple:
A few weeks ago, when a co-worker younger than me called me "Sir". I know it's a polite and respectful honorific, but the connotation these days gives it an "elder" feel.
Also, when the girls at Starbucks stopped hitting on me. I felt old.
And I'm only 27.
-_-
Wait till you hit 60 to feel old and have Jedi always reminding you about it.