warning message from Java client in YCSB

I'm seeing the following occasionally in a YCSB run against bolt80:
2015-05-08 18:04:11,337 (New I/O worker #22) [WARN - org.kududb.client.AsyncKuduClient.removeClientFromCache(AsyncKuduClient.java:1409)] When expiring TabletClient@495078094(chan=[id: 0x1ce93d04, /10.20.134.115:50419 :> /10.20.126.101:7051], #pending_rpcs=0, #rpcs_inflight=0) from the client cache (host:port=10.20.126.101:7051), it was found that there was no entry corresponding to /10.20.126.101:7051. This shouldn't happen.