Found this 'Lemon Frost' today in my favourite hosta nursery. I took a leaf home to test since I have test strips that need to be used up. But I also told the clerk and asked him to show it to the owner who is a real hosta addict and very aware of HVX.
I sent an email to the owner with a pic of the leaf and the positive test. His response was that he had already destroyed the plant I pointed out and another - there were only a couple of pots and they both had been old stock that he no longer knew the origin of.
The one thing that concerns me is that other staff obviously didn't recognize the symptoms and may also have tended to these plants and gone on to others w/o cleaning tools.
Moral of the story is to remain vigilant.