As I am watching the movie, Megatron says to Sentinel in Chicago, "this is the victory I promised you long ago." Then for no reason it seems Sentinel attacks him and say it would be wise for Megatron to know he's working with him not for him. In the end Megatron wants to be in charge, we all know that, but he has not revealed it yet. What was I missing? I didn't see a reason for Sentinel to go off and grab Megatron by the face at that point.