Hmm, I do run a NTP client/server combination which adjusts the system clock every now and then, but that's only a few seconds, not 14000 days...
The daemon has been restarted a few times after the DST change end of october, also syslog does not show major changes in the clock time, with the system being up for 145 days now. I'll try to see if it happens again in the coming few days.