That sign has been there for a year maybe, it's just not really talked about (like fight club). They do seem to enforce it somewhat which makes me happy. Also, for those complaining about Terminal D security lines, head on over to C for a prime time TSA run, it has to be the most poorly designed layout. Although wide where all of the scanners are, the bottle neck in the beginning causes sheer pandemonium for those non-frequent fliers... and the elite line doesn't exactly help either.