thxita said:

so are you sure you didn't deduce that yourself and it became a memory in your head?

For years, IMDB had a reference to it in the alternate versions category. Unfortunately it is no longer present. Perhaps I didn't elaborate properly. I never claimed to have heard the line - because I didn't catch LC during the theatrical run and instead saw it on home video.

There was a forum discussion that I can no longer locate where people confirmed hearing the dialogue when they saw it in the cinema, hence my request for confirmation that it exists or is an urban legend.

Here are some other links where it's mentioned:

http://www.theindyexperience.com/films/last_crusade_alternate_versions.php

http://tvtropes.org/pmwiki/pmwiki.php/Film/IndianaJonesAndTheLastCrusade