I'm retaining some skepticism. The difference seems to be enormous - more than I'd expect. It uses up almost the entire SCPF.
One explanation could be that the halfway point used was off from where it should have been . Up and down averages in both directions would balance out if the halfway point was off by 3 inches, with one half being 199.92 m and the other 200.08 meters. How was the halfway point established?
Also, pavement quality could have had an effect, as could a difference in riding posture.