Also, my board was above 20 degrees C, so the gray pads are sounding less like tin_pest in my case.
I think that both tin_pest and intermetallic formation result in a change in the crystal structure. In the case of intermetallic formation, copper is entering the matrix but since it does not fit perfectly it causes things to reorganize. From reading various articles, I gather that a tin alloy does not suffer from tin_pest, but it is not yet clear to me what ratios are needed. From the reading it also looks like intermetallic growth is required for the solder to wet, but then needs to be limited by a nickel layer or a lead rich layer.
One thing I have concluded is that if I want to solder a copper wire (which does not have a nickel layer) I will need to use a massive glob of lead free solder so that the wire is fully surrounded, or use lead solder.
So this is making me wonder if lead is really a problem in electronics, I fully understand why to remove it from petroleum gasoline, and plumbing (although this may explain a hot water line that pulled apart, which was also very odd).