The problem is that the stores are not ostrich services, they are finagle clients, and thus cannot be stored in ServiceTracker.  The Index and Storage services are ostrich services, so they can close the respective index and storage handles to cassie, but the aggregates one does not have its own service.  My solution to this was to stuff it in the collector, but it's probably best to just close all the handles in the collector service (which is then tracked in the service tracker).