Ah, question answered then - indeed a canon-continuity error. Ah well, like I said somewhere in this comment section: The Carver era of SPN seems to not really care about canon-continuity that much, which is really probably my major criticism of it.

And thanks for the biblical reminder - I honestly couldn't remember the story well enough to remember WHY she was turned to salt when she looked back, or why it was important for them not to look back, or why that rule was made in the first place.

I know the greek myth with the dude getting his girl from the underworld better - even though for the life of me I can't remember their names. :P Anyway, that one also has to do with looking back and getting punished for it, which is why I equate the two stories in my head.