What happened to my thread?

Earlier today, after getting permission to post TEOWAWKI threads, I started a thread in the Musings sub forum, entitled 'Lights Out: power grid failure'.

When I checked on it, I saw a 'pending approval' type of message with a shield image next to it. I checked back later, and the thread was just gone. Could one of the Mods please find out what happened to it? And why?