That's curious.
First off, the only thing that will make a wheel "wobble", other than getting ready to fall off, is a bent rim. If both tires stay at the same angle to the ground through a complete revolution, it is not a bent rim.
Finally, the angle of the axle/hub/rim/tire, to the ground, is set by the bore in the housing. Unless the housing was bent/broken on both sides, it is what it is. I assume you've jacked the rear and tried to make the tire/wheel rock on its axle? If the bearings had collapsed on both sides it might rock but it would also sound like a coffee grinder if you moved it.
I suppose I would set the tractor on dead level and use an accurate 3 to 4 foot level on the outside of the tire and compare how far out of plumb each side is. There is plenty I've never heard of and angled rears is one of them but if they are both the same angle to the dirt and there is no other evidence of a problem, there most likely is not a problem.
