Does "report two mile final for runway xx" imply a landing clearance? I know I am going to land. The controller knows where I am, but I am not cleared to land. I think the same logic can be said with a vector or altitude direction from ATC. It is up to the PIC to maintain situational awareness as to the boundary's of Bravo. If you feel you are going to enter it and have not received the clearance just ask. That way you are not on the hook if the controller messed up.