Resolution:
This message is a normal part of GMD. The subscribing server has been told by the publishing server that it no longer needs to buffer GMD messages for client X on subject /foo. RTserver Y keeps information for its direct publishing RTclients using GMD. It queries all other RTservers in the cloud asking them what other RTclients are directly connected to those RTservers, and if any of their RTclients are subscribing on the subjects that the direct publishers are publishing on that are connected to RTserver Y.  RTserver Y then keeps this information in a table; and, this information is retained until:
1. All direct publishing RTclients disconnect
2. If no direct RTclients publish to a subject with GMD in Gmd_Publish_Timeout seconds.