The possible cause of that on the radian is a loose grub screw in the hexagonal aluminium adaptor, allowing the entire prop spinner to wobble.
Its the aluminium 6 sided piece just above the screws in the photo link
. Check the grub screw in that, and tighten if its loose. You just need to remove the cone from the front of the spinner to get at it.
Im not a fan of that setup, we changed it on the sons radian, to an aeronaut setup, which has a proper collet, far better. Although the reason we changed was because the original radian prop blades on the early ones were prone to breaking in flight, which happened us twice a couple of years ago.