I'm also 53 and probably as competitive now as I ever was !! (3rd overall in this years club championship) so not too shabby
I've seen quick guys leave the hobby and come back after a few years expecting to jump back in where they left off ... it doesn't happen !! But over time they usually get a lot of their pace back .. but the older you are the longer it seems to take ..
and I think with age you tend to approach your racing in a slightly different way too ... more brains than balls out ... use what you have to your advantage
but most of all enjoy it !!
Big up the oldies !!