Giving the bike a good clean after a fun filled weekend riding around Canberra I found this; Luckily I'm a bit anal about cleaning things and took the cranks out to give the chainrings a proper clean - I'm guessing a bad crash was in the near future had I not found these cracks this early.
Weird thing is the cracks are on the top of the swingarm not the bottom; not sure how these formed as the force of my weight should crack from the bottom.