hmm OK, thanks for helping me find a bug then, lol. You shouldn't get ping since you had no messages in this room and you were not in the room when I posted the message.
So the bug is that moving messages doesn't cause a synchronization to happen, meaning the list of pingable users isn't being updated.
(when someone does have even only one message in a room, they can be pinged for one week even when leaving the room.)
I'll try to post bug report about it.
