MARK in /var/log/messages

I am getting a lot of "MARK" messages on several of my Debian boxes. I
have read that they are heartbeat type messages for syslog saying
everything is running well, but I have never noticed them until
recently, is this really normal or is there a problem with my system?



Jan 9 10:51:16 sid -- MARK --
Jan 9 11:11:16 sid -- MARK --
Jan 9 11:31:16 sid -- MARK --
Jan 9 11:51:16 sid -- MARK --
Jan 9 12:11:16 sid -- MARK --
Jan 9 12:31:16 sid -- MARK --
Jan 9 12:51:16 sid -- MARK --
Jan 9 13:11:16 sid -- MARK --
Jan 9 13:31:16 sid -- MARK --
Jan 9 13:51:16 sid -- MARK --


Jim