Fractured guess. They are running short of chips, so they went back into the vault and found some they could use. Right before Ho Chunk put out the current chips the old "Golden Nickle" chips appeared on the tables. Some kind of sting as some collectors bought these with the understanding that they would never see play again. OUCH!

So maybe these are in play until the next refill shows up from Chipco.

Only 150 miles from here. Should I take a chip run on the outside chance I can find some of the black number chips? Naaaah! ;-)