Divin'Hoosier:Does it just wipe away, or does it appear to be set into the finish of the tank? The dust I referred to in my previous post just wipped away, and as I said, I never had any "blow out". It was just a little bit of light dust on the tank threads. Is it like a powder or more like a liquid?
The easiest thing may be to get a visual inspection. They cost what $10-$15 maybe and include an airfill. May be worth the effort.
Sorry for the delay in my response - but it turned out to be just dust. Thanks to everyone for their help!