"Retcon is a shortened form of retroactive continuity, and refers to a literary device in which the form or content of a previously established narrative is changed."

That is the literary device they used. But they still changed a previously establish narrative, it is a retcon.

Not to mention that One New Day retconned Brand New Day on how it all worked because they bungled it up the first time. The writers wanted more freedom away from him being married plain and simple and they shoehorned that load we got to get there.