Nice photo Steve. I ended up with kinda the same experience there, but a few years later. It was in the summer of 1968 and when I walked by the firebox of 2-6-6-2T 111, I sensed some heat and sure enough, the outside sheet had some warmth to it. I asked a mechanic what had been going on, if they had been using her and he told me that she recently had been fired up and ran around the yard with abrasive brake shoes so the tires would pass inspection for her upcoming movement on her own wheels down to the California Western.
Glad you found those photos.