All i see in the master log is that the node is not responding to the /chain/height requests that are used for the responsiveness test. The log looks like this:
2018-05-12 22:27:59.856 INFO Responsiveness for node Yggdrasil: 10/10 (525ms) (org.nem.rewards.master.task.ResponsivenessTask lambda$null$49)
2018-05-12 22:27:59.873 INFO Responsiveness for node nemster: 0/10 (541ms) (org.nem.rewards.master.task.ResponsivenessTask lambda$null$49)
2018-05-12 22:27:59.906 INFO Responsiveness for node Neonoda: 10/10 (574ms) (org.nem.rewards.master.task.ResponsivenessTask lambda$null$49)
Maybe the NIS log of your node can help. Could you provide the log for that time?