Nostalrius Begins - Quality wow vanilla realm (1.12)

My account was banned for the reason "Flag exploit in AV - Senshinriyu". Not exactly sure what this means but regardless, my account homepage says I was banned up until "August 11th 2015 22:30:24 PM". If this is a mistake and I've been permanently banned, I would like to have a full explanation on what a flag exploit is (because I have no idea what this is) and why there wasn't a warning by a GM before handing out a ban, Thank you.