Scott just posted this article up on the team blog..
A summary of the issue…
“This hotfix is strongly recommended for all database availability groups that are stretched across multiple datacentres. For DAGs that are not stretched across multiple datacentres, this hotfix is good to have, as well. The article describes a race condition and cluster database deadlock issue that can occur when a Windows Failover cluster encounters a transient communication failure. There is a race condition within the reconnection logic of cluster nodes that manifests itself when the cluster has communication failures. When this occurs, it will cause the cluster database to hang, resulting in quorum loss in the failover cluster.”
If you haven't already picked this up I strongly recommend taking a look and assessing if you need it on your production clusters.