"BGP: Unexpected connect from unknown address" after joining new node

Cluster information:

Kubernetes version: v1.14.2
Cloud being used: bare-metal
Installation method: manual
Host OS: centos 7
CNI and version: calico 3.3
CRI and version: docker Docker version 1.13.1, build b2f74b2/1.13.1

Hi, I am new to kubernetes and trying to get familar with it on a bare metal cluster.
Some days ago I installed 1 master and first worker node worker#1 with calico network. Today I joined a worker#2 . In journalctl of worker#1 I can see following output each few seconds:

kubernetes03 dockerd-current[15237]: bird: BGP: Unexpected connect from unknown address x.x.x.x (port 51430)

the given IP comes from the newly added worker#2.

What can I do to get rid of this journal message?

Thanks, Andreas