Glad it was you who was first, our server admins don't show much interest during upgrades as the persistent ports stuff just makes it transparent and they are used to it just working.
Out of interest did you run a showhost -pathsum while the Node was down?
Typically during upgrades I watch the port states on Brocade/HPE SNA (go offline then come back) and once down do a showhost -pathsum to confirm which hosts have reduced number of paths, also a shownode.
Once the ports come back I do shownode till it's back in the cluster and then another showhost -pathsum to check all paths are back.
I'm assuming with this bug everything would have looked normal with the 3PAR checks but at least my fabric check would have been big red light.