Thanks for the tip. Checked "nodetool ring" on all nodes and they all have a consistent view of the ring. We have had other problems like nodes crashing etc so anything could have happened, but we're sure we didnt issue a "nodetool move" command.
From: Tyler Hobbs [mailto:firstname.lastname@example.org]
OpsCenter just periodically calls describe_ring() on different nodes in the cluster, so that's how it's getting that information.
Maybe try running nodetool ring on each node in your cluster to make sure they all have the same view of the ring?