I think it is new to the CGC world and, as noted before, maybe part of the collection of other DC keys in this auction (also noticed the first Lois Lane #1 to reach the 8.0 tier is also new to CGC census and is in this auction)
The Beth. Showcase #4 passed through a couple of West Coast collectors after Joe Rainone decided to sell his piece of the Bethlehems in the early 90s. Perhaps one of those is the source of these in this auction.
On a side note, interesting to note that the date stamp on the back cover of the Beth. Showcase 4 says "JULY 12, 1955" (instead of '56)
Maybe the Silver Age started a year earlier!!