I don't think so. He elaborated on it a bit.

In the bible, it says when the devil claims a soul, it is taken from the back of the neck. Hence, the bandaid on Ving Rhames neck in the initial shot of him.

Also, a soul is supposedly the most beautiful thing in existence, which explains why whenever anyone opens the case, they can do nothing but stare in awe.

There were a few other things he mentioned, but I don't recall them all anymore. I don't think he was kidding or 'making it up', I think he was telling us what was in the case.

Yeah I heard this as well.

Read it in a mag where they interviewed QT

I think you're right. The soul thing was an internet rumour way back in 94 that Tarantino alway blew off and said wasn't correct. Now he seems to have adopted it. A case of pop culture folklore becoming fact.... perhaps another case of Tarantino putting "his spin" on other people's ideas again?