I also mostly follow this pattern also. As I imagine throwing with my left arm and right arm, the left arm feels a bit "numb" comparatively, like my brain doesn't have as many neurons devoted to controlling it or reading information from it. I can't describe it very well. I wouldn't imagine anything unique in that, and a left armed person could just as easily feel that imagining doing those things with their right arm. It just feels odd to pay attention to the difference in how my brain processes both sides.