If I were charitable, I'd say this was a computer screw up? Or, in one of my less charitable thoughts, PERS simply picked arbitrary beginning and end dates and had the computer spew out as many of these notices as there were retirees in that particular time frame. Let's do a perp-sweep. Computers make this easy. Of course, computers also make it easy to exclude people, but that would require that the programming be done in something other than a purple haze.
P.S. And speaking of purple hazes, I just got a notice from another retiree whose husband received his "Notice of Board Order" last week (a pure "window retiree") while the spouse, also a retiree from the "window" but under Formula + Annuity did not get a notice as of today's mail delivery.