Security enabled layer

Hi
I have 5 map services that one map service has security and this layer is off by default and other layers have not security and they are on by default. When I run flex viewer 3 for first time the authentication page appear for log in to security enabled map service. I don't know is it possible that when user going to turn on that security enabled service, the authentication page appear. if user don't turn on that layer the authentication page don't appear. I mean authentication page appear if need( if layer should turn on the authentication page appear).
Regards