Please mark Oliver’s answer as topic solution!
Let’s see if the previous log files matche too…
grep NsReleaseLock /var/log/messages-*
And also
grep nethserver-check-nsreleaselock /var/log/cron*
This action was expected to switch the policy to “locked” automatically tonight 
I’d say we’ve a Bug here: it runs after 0yum-cron! See ls -l /etc/cron.daily/.