It was a thread locking solution they used on the barrel threads back then. Took them a while to find the problem and it was only a problem if they were locking solution was put on the revolver threads on a Friday and not assembled right away and set all weekend.
I would not worry about it, if it happens (probably not) Ruger will replace it.
If the barrel hasn't fallen off yet it's probably not going to.
What you're describing seems to have been a rather rare phenomenon that was in the end remedied. First by adding the Super Redhawk to the line-up with it's super beefy and supportive frame, and then by discovering and correcting the assembly line issue with the Redhawk.
I too have an '80's Redhawk. Mine has many miles on it and still going strong. Use and enjoy your 'new to you' Redhawk. It should last your lifetime and more.
Thanks for replies. This gun has been shot very little, appears to have been a safe queen. I plan on shooting until it or I am worn out, the barrel falls off, or whatever. I have 2 blackhawks, and a S&W 657 in this caliber, and have been looking for the Redhawk for some time.