After Harder exercises I can feel a strong pulse, exactly between my ribs (about the center of my upper body without the head). If I lay down on my stomach, I can feel it "hitting the floor" (I'm not sure how to describe it). After I calm down, the pulse almost stops, although i can feel it when i press on the point. When i lay down, I sometimes can see my ribcage moving on its own (without breathing), but it's barely noticeable. Should I be worried? Could it be aortic pulsation (and is it normal to have one)?