That Gallup survey doesn't really scan for me. If you had told me in 2001 that 35% of my generation were smokers I would not have believed that. There must be a huge regional component to those survey responses.
(These days things are different, fortunately. I don't see many young people smoke anymore, but the mentality was completely different back then, around the time when it was still allowed to smoke indoors everywhere)
I'd honestly guess you either didn't notice them or forgot that they smoked. As a former smoker the bars were filled with people smoking until the indoor bans when you could always find some outside.