Gluster users - Aug 2018 - Error after upgrade 3.12 -> 4.1 : Maximum supported op-version not set in destination dictionary

Hello there,

i just installed a replicate setup to test if the upgrade 3.12 -> 4.1
runs smoothly. Well, it did :-) though there is no real usage/load on
the test installation, just some test files. I upgraded from 3.12.12-1
to 4.1.2-1 on a debian stretch. Besides some warnings and errors
(disconnected peers during upgrade) I only saw one error message:

[2018-08-21 12:45:12.865749] E [MSGID: 106061]
[glusterd-utils.c:10170:glusterd_max_opversion_use_rsp_dict]
0-management: Maximum supported op-version not set in destination
dictionary

In https://docs.gluster.org/en/latest/Upgrade-Guide/upgrade_to_4.1/
there's the point "Post upgrade steps" ->
https://docs.gluster.org/en/latest/Upgrade-Guide/op_version/

gluster volume get all cluster.max-op-version
Option                                  Value
------                                  -----
cluster.max-op-version                  40100

Is this a real error? In the production installation it says:

cluster.max-op-version                  31202

I would have expected something like "cluster.max-op-version 41200"
for gluster version 4.1.2.

"gluster volume status all clients" shows the same, e.g. (3 servers, 1
client):

Clients connected : 4
Hostname                              BytesRead    BytesWritten     OpVersion
--------                                     ---------
------------           ---------
192.168.xx.yy:49121             30188            39244                40100
192.168.xx.yy:49147             1896              2812                  40100
192.168.xx.yy:49148             1508              1844                  40100
192.168.xx.yy:49138             52780            29608                40100

Just curious :-) Or did i miss anything?