I also owned a brand new red Westone "The Rail" in ... 1992 and I've always been picky about ground noise.
The one I had had no ground issues, but when locking the pickup block into the desired position, I always noticed a kind of spring resistance with the knob, so I guess the metal tubes were grounding the bridge and that the locking screw was in contact with the output jack ground through a wire soldered to the metallic thread of that locking system.
As a side note, the screw was bare and leaving slight marks on the metallic lower tube where the contact was made.
That said a good grounded shielding of the pickup cavity helps a lot too.