Thanks for posting that story. I never knew that about the 1991 limited edition Caesars chips -- probably because I was still too young to legally gamble then.
It is true that chips can be taken out of circulation at any time, with a limited period of redemption.
This is why poker players who store chips in their safety deposit box (or take them home) are foolish, unless they go to the casino regularly.
On a side note, it is always a mistake to take home 5k chips, because casinos will question you when you go to redeem them, and they will confiscate them if they don't believe your story.
Bellagio once had the nerve to threaten to confiscate a $5k chip I had won just the day before in the poker room,
after I had been sitting in their game for nearly 24 hours. I won a bunch of chips, so I let someone swap his 5k chip for two racks of $25 chips when I was ready to leave (which is allowed). I took that chip home, then came back the next day and cashed it. They didn't believe I had been playing the day before, and the floor manager insisted that he never saw me. We got into a big argument, but finally one of the dealers said that he remembered me in the game, and the manager rudely uttered, "Fine, cash it" to the cashier, and walked away. This was about 10 years ago, and I've refused to take $5k chips ever since.
Nolan Dalla also infamously
had a $5k MGM chip confiscated when he admitted that the chip was given to him by a friend.