Hmmm........"anything to worry about"....Hmmmm. Below the crack there appears to be a wedge of metal missing, is that true or is that an optical illusion?
After looking at it more closely, I see that the wedge portion is where the shift lever (where it attaches to the ratchet mechanism) smacks the bearing holder during a violent quick-speed up-shift. It looks as if the crack is from the outside in toward the bearing rather than from the bearing trying to break free from the bearing seat. If you are not planning on racing this bike, I would just leave the crack alone and monitor it each time you replace a kick start spring or kick start pawl.
Send that ring to fires of Mount Doom!