Nope, there was a 20 year old elected in the 70s. But what is unprecedented is the sheer amount of people who got in this election who are, what some would say, unqualified.
Me, I'm happy about having fresh people in parliament who have yet to become politicians.
Although is wasn't my favourite politician (for my own provincial reasons shall we say) Brian Tobin started out very young. I believe he was in university or dropped out and was on a local radio station for a bit. One has to respect his accomplishments.