Yes the salute is and early Christian salute it was covered on one of the DVD I have the entire set. And I think it may have been on a quiz on the DVD ? Next time I watch them I will let you know, more I could not find anything on Wikipedia . The shape that is made with the hand is supposed to be the shape of a fish!
It is interesting to note that the shape also looks like V.F.D. from "Lemony Snikets a series of Unfortunate Events" I don't think that there is a connection it's kind of neat. be_seeing_you.jpg