Rand hasn't figured it out, nor, it seems any of the (unturned) Aes Sedai visiting. It may not be very subtle, and the mistresses of Daes Dae'mar are kind of idiotic to miss it, but it's not like they have a sign up saying, "All Dreadlords Form a Line Here". It just seems like pretty small potatoes for Demandred at this stage; openly or not, the Shadow's doing a booming business at the BT, and I'm not sure what Demandred really adds to that equation, especially since he's got plenty of other more pressing duties that he can't delegate.