
Originally Posted by
Gadget
I can't promise this is true, but i remember being told that it was a signal used right from the beginning which had been adapted from a similar set of hand signals used by the army for reconnaisance missions where silence was vital. there a hand raised to head height, forward from the face and palm flat was used to signal that a message was about to be relayed.
not sure how true it is and i can't find anything to back it up online and i can't even remember who told me that but it seems to fit.