Chip was the $1 pink H&C from Casino Club in Redding, CA, very worn to begin with. Looking through my album after a couple of years, I saw with horror that there was clear goo coming out of the chip (or the flip) and the outer ring seemed to be "melting away." I have not seen this with any other chip, and the surrounding items in the album (stored in the same type of flips) were okay.

I washed the chip and let it remain in the air for about a month, before returning it to the album in a new flip. Will continue to monitor that one to see if the problem returns. What could that have been?