I think you should have made the effort to do 0.8km more to reach exactly 100 :)
My Garmin said I was at almost 101km, but some distance was lost when tidying up the route. 100km isn't the big line for me as it once was, anyway. More interesting to me now is a ride that improves on my Eddington Number, which at the moment requires a 108km ride.
My Eddington number's just 23 :)