i think what he is trying to say is that before when you didn't have service it would say "error sending message" or at least thats what it says for me when i try to send without any bars.
Nope, I got the same message too when I am in the library where there is spotty signal. When I hit retry, I guess it sends it again..recipients got duplicate messages from me, some just got some one message from me.
I think I can recall seeing that screen only on the occasion that some of the recipients in a multi-person message didn't get the message before losing service.