Source please?

I don't think it should be a special based on the contribution bible's definition:

Special episodes are any episodes that did not originally air as part of a regular, usually numbered season. Sometimes a network will call an episode a "special" episode—as an example, "in this special holiday themed episode"—but still assign it a season and episode number; in those cases, it should not be added to the special season here but, instead, to the season assigned to it by the network.

It aired along side all of the other episodes. It shouldn't matter that it just happens to be extra long.