I had one just like that and it did the same thing. The scales just absolutely disintegrated in days! I peeled them off before much damage was done to the metal parts.
Mine is an XX USA model and here it is today:
It's one I rehandled myself out of Montana Mule Deer stag, and was once my favorite EDC. It since has been replaced by GEC 73's with the single blade, as I'm still waiting for them to make a 73 with drop point master and secondary pen. The 73 frame is about 1/2 inch shorter and the blades are the same length.