John; This phenomenon occurs not only with the RES-1. I've seen similar inlay color changes on Park Place, Brighton and Atlantis $1 chips, all of which I have illustrated in my A.C. catalog. Here is a Boardwalk Regency $5 chip with same discolored center inlay.

Does this happen on Las Vegas chips as well?

The owner of the RES-1 chip tells me that it has been in a dark drawer for over 20 years! Maybe it has been laying on some of that cedar plank that you showed in your orchid posts?