They were following the same Daygame model that everyone else on this forum follows.
Also, I should probably mention that they still had spots and braces, so its not like they looked way above their age.
I'm 20 (ie. one year older than you) and have been doing this about a year. I've never had a girl ask me how old I am, its never been an issue.
I suspect this is one of those cases where you are looking for an excuse not to approach. On one level you know that its a bit silly, splitting hairs (being 19 and not approaching 20 year olds, seriously?), but on a deeper level, you have some approach anxiety, which is manifesting itself in illogical excuses.