.BridgeCache and .BridgeCacheT invisible files on mounted drives

It was my understanding that Bridge saved its cache files on your local HD in the location you choose in preferences.  But when looking over my server backups of networked drives I'm seeing invisible .BridgeCache and .BridgeCacheT files in every folder someone has accesses via Bridge. What gives?

Note:  We're running High Sierra on workstations and networked drive are Linux/Redhat.