When you don't have a rooster in your flock, a hen will usually become flock master and take on many of a flock master duties. Occasionally one will demonstrate her dominance by actually mating another hen, even to the point of touching vents. They do not all do that, most do not do that, but occasionally one will.
I don't know if your hen followed up with a mating attempt. Even if she did it does not mean she is twisted or bent. She does not need therapy to help straighten out her sexuality, she may still lay well. But I agree, it's just a dominance display.