Grandfathering was for things like 4" and less handguns back in 1995 when the laws really changed (licensing, 5/30 AR mags, registry, etc, etc. - all b/c of that dirtbag that killed 14 women in 1989 at Ecole Polytechnique in Montreal with a Ruger Mini-14). You can also have the 'prohibited' class added to your license if they are inherited.
The 14" 590 I got back in 2002 was never an issue though, and still 'non-restricted'. I don't shoot much anymore, and my 590 has been in the safe since 2005. I can still feel the pain of shooting a few 3" magnum slugs through it. The plan recently was to sell it, but am back and forth on it.