Margaret, no, you should not expect any poly seedlings by crossing an errant polymerous bloom with another standard daylily. All daylilies have the ability to throw an occasional, or once in a lifetime, poly bloom but that individual poly bloom does not increase the likelihood of producing polymerous seedlings.
However, if you used pollen from a recognized high percentage poly on that errant bloom then you may produce some seedlings with a great propensity to express the polymerous trait. This would be the same whether you were crossing onto an errant poly bloom or normal bloom on the same plant.
The best way to ensure success in producing high percentage polymerous daylilies is to breed high percentage polys with each other.
If you have have not already, I hope you will obtain some polymerous daylilies and start hybridizing with them. We really need as many people as possible working with the polys to advance the development of this form.
5 Chamber Seed Pod from SWIM BIKE RUN which I expect will yield all high percentage polymerous daylilies!!
