Dick,
Thanks for posting that. Now that I see it, I think you posted it before... sorry for my short memory. It does look very conventional and, since the spanwise datum line for the wing is ahead of the 50% point at the root, it's not at all surprising that you can fly it well at 40% of the root chord. Eyeballing it, that will be in the 30-35% MAC range. Very normal for an aerobatic plane. And no, I'm not saying this to dispute your observations... just making an observation myself.

-David