I know some coders in their 60s that just like you have a fresh mind and are still eager to learn new things.
I believe association with older people being less capable of mental task and creativity stems from how our society works (or rather worked). People used to do the same job, then become some grandpa with not much input or challenges to keep their brain active. It is quite well documented at this point that when you keep challenging your brain there is not all that much degradation coming with age. It's just that as you get older it's becoming harder to present something really new to your brain - it will tend to view it through existing patterns and use shortcuts that you already have. That's why picking up some new language (not just programming lang) just for the sake of learning something new is a good idea (but what for? could be for fun - dopamine is a lot of fun)
* The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science - Norman Doidge ( http://www.amazon.com/The-Brain-That-Changes-Itself/dp/01431... ), great book