I called the supplier. The company representative who took the call said that he was positive that this damage was caused by our late cold snap. I had brought the plants indoors on the worst nights, but maybe the days were also too cold.
I'll definitely keep these in rehab until they look completely normal. I'm not entirely convinced that they're free of disease. In the past I've had lots of frost/freeze damage on my garden hostas, and this still strikes me as different.
