Just fold up your sign and don't let them "know" that you have a sign when you go through security. We made one before we went in to DLR in March and they very nicely told us we couldn't bring it in at security. So fold it up and put it in something so that it isn't immediately apparent that it's a sign.
However, our DS 12 did get picked, without the sign, but DS 5 did not and he was very bummed. We will definitely be bringing a sign with us the next time we go. We just will fold it up and stick it somewhere. lol