I'm 27 and I look a lot younger or so I'm told.
My Picture
When I shave I look even younger, under 21. It's hard for some to believe that I was a cop full time (now just part time).
So far my treatment has been fine no matter how old I look or what I wear at the airport. (normally jeans when I fly)
BUT, I agree. I normally see some age discrimation but I just haven't at the airport as of yet. Probably because I don't fly as much. I know my wife and I got a lot of stares when we were in first from LAS to CLT. I think people thought we had rich parents or perhaps we were on a honeymoon. Actually neither...just a vacation.