Warnings in Error log on a Slave/Master node

Hello- We have a 3-node Percona XtraDB (5.6.34) cluster set up, with a slave server hanging off of one of the nodes. We also have this slave server (also running XtraDB 5.6.34) set up as a master as we use it to replicate to an off-site DR Percona server. We noticed that the below warning started showing up in the log on this slave server last week. The warning shows up numerous times every second. I have not been able to find much online in regards to this warning. I see the warning mentions WSREP, which has to do with Galera, but this slave is not part of the cluster. I have verified that the replication is running fine on both this slave, as well as the DR slave, as I see current data on both:

=> Skipping replication
2017-01-30 08:47:05 14855 [Warning] WSREP: SQL statement was ineffective, THD: 2, buf: 276
schema: (null)
QUERY: (null)
=> Skipping replication
2017-01-30 08:47:05 14855 [Warning] WSREP: SQL statement was ineffective, THD: 2, buf: 329
schema: (null)
QUERY: (null)
=> Skipping replication
2017-01-30 08:48:08 14855 [Warning] WSREP: SQL statement was ineffective, THD: 2, buf: 407
schema: (null)
QUERY: (null)

If anyone has specific info on what this warning means and how to fix it, I would appreciate the feedback- thanks!

Ron