Nice pace ! But very strange to be 26th in age rank if you are 9th overall ?
Ye it is age grade, not age group (I would have won age group). Age grade is a formula that tries to adjust your time for age and gender to "level the playing field".
I have a little calculator you can play around with at wardje.eu/run/calc if you want to.
ah ok I understand, I knew this principle, but strange to give prizes based on it, never saw something like this ! bad luck for you ;-)