I was just talking about this over the weekend. In my almost 30 years of (legal) drinking, I have never been asked for I.D. Some people you talk to are carded all the time.
My 36 year old Sales Manager was carded 3 times recently in one weekend!
Take a look at this video and see how hard it is to tell by appearance alone, how old a person is.
The moral of the story…don’t take it personally. Bartenders are just doing their job by asking your for I.D.