I noticed a rust stain on the first few pictures showing the damage.
Wonder if that stain's appearance indicated some sort of crevice corrosion prior to the ultimate failure?
I will certainly not claim to be an expert, but there are many people who believe exactly what you describe (rust is a warning sign of a deeper problem with stainless fittings).
Very wise of Jill to proactively manage this, in a very organized manner.
Mike
