I Have Developed a Dimple in the Middle of my Nose Which Becomes More Defined After Excercise, Why?

I have recently noticed the development of a dimple in the middle of the tip of my nose. The dimple seems to be where the cartilage and the nose bone meet. When I wake up it is not there but becomes more defined during the course of the day and even deeper and more defined after excercise, with the tip catilage looking noticeably "split" down the middle orginating at the dimple. What would cause this?