Yup. Repacked the bareroot plant with some damp paper shreds to keep the roots nice and moist. Packed it securely in a Fedex box, filled it with packing peanuts for cold insulation and crush prevention, then shipped it back yesterday morning.
Although I know that the nursery knows what RKN is and looks like, I left a big note on the outside of the box with some RKN information and spread prevention tips, then asked for a callback when the nursery confirms it was RKN so we can work something out. I told them that if they have no clean Marseilles or Conadria left at the nursery (the two varieties I'm interested in right now), maybe I could just have a credit towards an RKN-free plant next year. $10 credit is what it would boil down to because I owed the shipping to get the plants here ($11), but I paid for the infected plant ($15) + my return shipping ($7.50) ... $22.50 out of my pocket, $11 out of theirs. They can always re-root any cuttings from the plant and possibly recoup $45-60 next year on those roote cuttings.
I'm sure it'll all get worked out. I'm not mad about it, I'm just still incredibly suspicious of the source, and as gorgi said earlier... I'll be treating the other three plants like they're radioactive material as well. I cleared the roots of soil and repotted in my own (clean) soil, so ... should they bear signs, it's probably due to some trace I missed when cleaning, or something they aquired in the days prior to shipping. In that case, I'll be hacking off the roots and trying to root the resuling cutting(s).