I mean, chronologically, that would make a ton of sense.
He got into the fight with Shodaime and looks regular, with two eyes, then after the fight, he disappears.
After THAT he somehow becomes the Mizukage.
Than AFTER THAT he re-appears, and suddenly has a mask covering his face and exposing one eye.
The only thing that could be wrong with that is the fact that Kisame didn't recognize him with the mask on, if he had the mask on while he was Mizukage, Kisame would have known right away.
BUT Madara has been shown to change his masks as well, and he has also been shown to change his hair, so maybe that's why he didn't recognize him?