So I did more reading after writing "A Box Full of Honey."
It turns out that queens take LESS time than workers to hatch out. So...probably the queen cells we saw in the Sylvia hive were formed before half the hive swarmed. I'm still thinking there is a queen of some sort in the hive, since the bees are calm and not cranky. She may be one of the queens that hatched around the time the hive swarmed....which would mean that she is only now getting down to business. It takes several weeks for a young queen (a virgin queen) to mature, go on her mating flights and settle into laying eggs.
I may poke into the hive today and see if there are any eggs or brood. Or I may just let them percolate another week or so and then check after the May honey flow is good and over, and prior to the July honey flow.