Hi "I got my own thread!" :)
I found the cause but not sure if its solvable.
My pfsense is a guest in a Windows 2012 R2 Hyper-V. A reboot of the pfsense made the clock take a jump, backwards. ::)
Running the update script manually show this:
ERROR: /var/db/rrd/ovpns2-traffic.rrd: illegal attempt to update using time 1483895952 when last update time is 1484149652 (minimum one second step)
1484149652s-1483895952s=253700s, ~1h10m …
I had the guest-service for the guest machine turned off in Hyper-V because I wanted pfsense to manage the time through NTP by it self.
I'll proceed with some trial and error here to see which combination of time-sync that's working in my setup.