I had this same thing years ago on a daylily "Plum Perfect" that I have since learned was never registered. I bought it as an All American Winner from 2003. I didn't know until this year that it is not registered. I was looking it up for stats and found that there is a new "Plum Perfect" registered by Maryotts this year. Mine is a 3.5" plum on a 24" scape. The second year I had it, I got 80 something prolifs off it. Some scapes had as many as 10 prolifs and they had blooms, too. I've never had another one!!!! It was like it put out all it's energy making babies and it never did it again.
Now, I wonder if it had the year before I bought it, had BAF used on it or something similar. Just a thought???