Of course, you are right Igor, the command just set the permission and nothing else.
I decided to wait but I still had the same message showing up the next day. Then I tried to do a manual update and that worked like a charm.
Didn't I wait long enough or do I have some trouble with the daily cron? You see, I have got the same cron message "run-parts: /etc/cron.daily/log2ram exited with return code 1" every morning now for some time but cannot recall when it started. Could it be related?