Sometimes they don't bloom with horns. That seems to happen more with iris that have short horns. That said, Petal Pushers bloomed with no horns for me, but often has very long horns.
Some iris, like Kid Power, are chosen by the hybridizer because they consistently grow horns. Other iris, like Thornbird, run from short horns to horns with spoons on the end. I think their growth is affected by weather stress and the such, so you will get a gamit like you have with Unfinished Business of short to long. Some people say too that the best horns and flounces are produced in the first blooms each year. Not sure if that is true or not. Thornbird is much less likely to have spoons on the later blooms, but Kid Power had huge beards to the very last bloom.