I went into RHO today after shooting, and the NIB repro that a member friend traded in sold almost immediately. Ryan looked it up in the book and reported the SN as 00627. Then, a brief period of lucidity told me I actually listed the gun here:
https://parkerguns.org/forums/showthread.php?t=36256
and the photos I posted in that listing clearly shows the SN. No '20-xxxx' or P-xxxx, just numerals. I had never seen this before, nor have I seen another similar example since