Currently, the setup warning count is stored on the host, usually in APC. This is used to show the red "setup warnings" banner.
When multiple web nodes are in service in a cluster configuration, this warning can be cached on all of them and need to be cleared individually. This is annoying.
Better would be to make a database cache authoritative, and hit that if we see the flag in APC, then clear the flag from APC if it has already been cleared by another host.