Huh, this is interesting.
I've noticed the "characters younger than ourselves" phenomenon for a long while. Players age, their characters never seem too.
I'm 31, and I can see someone my age deciding to set out to adventure as a novice warrior, or wizard, or what have you. But it's rarely played that way in game - despite the fact that many characters in fiction are "old and grizzled", and despite the fact that most action heroes in film are in their 30's, or older.
In a way, it's rather funny. Given the age of most starting characters in campaigns, and given the relatively rapid speed of advancement, the ranks of adventures are filled with 23-year old Gandalfs and 20 year old Aragorns - in d20, adventurers are like women's olympic gymnasts, over the hill by the time they're 20.
I'm actually writing a PDF about aging right now, which will publish through Ronin Arts. It's called "Heroes In Autumn", and it's all about aging heroes - I've added unique racial penalties and benefits for aging, written new options to make the idea of playing older characters more attractive, and there's a section discussing roleplaying themes and hooks unique to older characters.
Patrick Y.