What would cause my barely used green bearing to do this?

That happens when Green wheel bearings preload the differential thrust button. The custom axles are too long for the housing, or the OP is using a poorly designed rear disc brake kit. In both cases, tapered roller wheel bearings will not work either. The easiest solution is to install a new pair of snap ring Green wheel bearings and remove the thrust button.

BTW, Green bearings are made in Ohio.