It may very well still increase, I'd cut off the stalk just like you always do.
When I divide iris rhizomes, I will often leave at least a chunk of the mother rhizome attached to the increase. That way the cut is on the mother, not the child. If the increases are quite small, I think it's best to leave the mother in tact with the increases, hoping that it helps nourish the increases. No science behind my suggestion, just a gut feeling, you know, like the kind our president uses to make important decisions when he doesn't want to take time to check the facts.
