Further testing shows it works in GoogleMaps v=3.30 and v=3.31 but fails with the new(default) v=3.32
So you can use &v=3.30 or &v=3.31 and the map will work. Using the default or &v=3.32 will fail. Very strange.
I'm trying to dissect the mesonet-map.js code to see where the failure really lies. Meanwhile, the quake-json map works fine with the default, as does the global-map scripts (which use much of the same code).