Congratulations! If you're interested at all in doing a century, just gradually add a few miles and see if you enjoy that distance. If so, add more and check again. If you reach a distance that is no longer fun, then ask yourself if completing a century is really that important to you. If so, then go for it.
I'm still slow.... the more I think about it, I really don't know if I want to spend 8 hours on a bike. But the hot weather we're having might be clouding my thinking.
Specialized Roubaix Expert
Surly Long Haul Trucker