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

yellow rose said

Because the tapered bearing allows for bigger tolerances. If you run a locker or spool (I've run a locker on the street for years and the D60 will be getting a spool) you have to use the green bearing. There is nothing in the center of the carrier to let the axles butt up to.

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Using a double roller/ row sealed bearing with integrated cage and race are the way to go. The bearing in the pic is an older version requiring a bearing preload onto the cup such as in the adjustable flanged type /screw type bearing flange. Ive seen and replaced many mis identified bearings(parts supplier error) installed instead of intended captured case race double row and sealed non maintenance "Green" type.The width of the outer bearing race is the clue.... Cant measure the race from a out of scale pic. Good pictures though.