He added to 'Entertainment Tonight': "Some people maybe thought, 'Are you doing 'Better Call Saul'?' and I would just said, 'No, they're on a hiatus'... It was easy for me to keep a secret, but I just couldn't wait for the world to be finally able to see it. They're going to really love it."
The actor found it "amazing" working with the old 'Breaking Bad' crew in New Mexico again.
He said: "We were really truly such a family, and it felt like a crazy sort of messed up family reunion just telling the same old messed up story. It was a lot of fun, so much fun."
Asked whether the fate of Bryan Cranston's alter ego Walter White - who appeared to die in the 2013 finale 'Felina' - and whether he's alive or not will be addressed in the film, Aaron stayed cryptic.
He said: "No...yes... You know what:? To be honest, I thought that the show answered that."