lower anti-entropy send error message log level

Change-Id: I49c6aeafe11d8b9b6d7dfe1e1834189660a40864
diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStore.java b/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStore.java
index dac9cbc..5642ea5 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStore.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/device/impl/GossipDeviceStore.java
@@ -1136,7 +1136,7 @@
                 try {
                     unicastMessage(peer, DEVICE_ADVERTISE, ad);
                 } catch (IOException e) {
-                    log.error("Failed to send anti-entropy advertisement", e);
+                    log.debug("Failed to send anti-entropy advertisement to {}", peer);
                     return;
                 }
             } catch (Exception e) {