I must have missed the announcement of re-ranking of registry sets based on number of NGC vs. grandfathered PCGS coins.  My US Bicentennial Silver set was tied for first with several other entrants.  Now I am tied for fourth.  Same number of points, but the number one set is all NGC and second and third each have one NGC coins.  My set is all (grandfathered) PCGS.

In Mark Salzberg's letter of 11/10/2016, announcing the change to the Registry regarding PCGS coins, it was stated (emphasis added):

"To be clear, all coins currently in NGC Registry sets, including those graded by other services, will be allowed to stay in those sets. There will be no NGC Registry point deductions or rank changes for these coins or sets. Starting in January 2017, however, if you would like to add a new coin to an NGC Registry set, it will need to be an NGC-certified coin."

Guess I must have missed it when this change was announced.  Oh well.