Mine falls behind as well. (09 Ultra) As others have said, no big deal, but on the other hand, is it really asking too much for the clock to work on a 20K scooter? As far as I am concerned, if it does not work why put it on?:s
It's a feature, lets you justify spending a little more time on the bike. If you don't reset it, in a couple of years you have gained 15 minutes or so.