[syslog-ng] Syslog-ng shutting down

Recently, on a semi reliable schedule, our syslog-ng has started shutting down for no apparent reason. 3 nights in a row between 8:12pm and 8:20pm it shuts down. No, it doesnt crash, we get the 'syslog-ng version 1.6.9 going down' then it terminates. Before this, we had a few other times it just shut itself down... Now we havent changed anything on the system, theres no cron job running anywhere near that time... Has anyone else expeienced this? We've be running syslog-ng for 18 months now and this just started a few weeks ago. It seems very intermittent, but then this weekend, almost like clockwork.