I don't think I've ever seen an original rifle with a striped rod that I could with any degree of assurance conclude the rod was original to the gun.
Or even original to the time of use of the gun.
And like a lot of guys here, I've seen a huge number of Kentucky's over the years, but that doesn't mean I don't like striped rods!
A few of my rifles that were missing rods when I got them have nicely striped rods now, and I enjoy the look.
I use tape to define the stripe, (I like the long slow twist thin stripe style) then color it in with India ink. Once the ink has soaked in a bit and fully dried, I pull off the tape and buff off the ink until it gets the look I need for the gun.
If striped rods weren't original, they should have been!
John