Something started clicking when Madara joined the fight with Tobi for the first time. The reaction from Tobi's face wasn't what you'd expect from a student/comrade to his master/comrade. He seemed very reluctant that Madara had joined the battlefield, let alone being rezz'd. Now, they are starting to bicker. It is starting to lend some credit to the theories that have been presented on the Base. Tobi is all for the dream world because he can be with his Rin and all that, while Madara hasn't convinced me that he is wholeheartedly into that plan. Madara is cunning and egotistical. I just can't accept that he is going to put everyone in a deep genjutsu. At least not one that makes them sleep in some dream world. I think he is trying to make it a world that worships him and him alone. You can't tell me that he isn't still bitter about Hashirama being chosen over him or the Uchiha turning their backs on him. He was the co-founder of the village and Tobirama was chosen over him as the 2nd Hokage. They basically emasculated the co-founder of the entire village and reduced his status. In conclusion, there is a definite rift in their alliance and I think Tobi is either, starting to or has for a while, been very suspicious of Madara's intentions.