PM and Report seem to trigger it.
I have never done a PM or a Report.
Plus, limiting posting to 6 minute intervals seems like a bad idea to me - after all, I can well respond to two different posts with in a period of 2-3 minutes.
(E.g., this response is the second post to this forum within 2 minutes - well, it would be, if the 360 seconds bug wouldn't prevent it ... )