I am assuming the wobble was not present prior to the tire rotation?

The wobbly is generally tire related; wheel weights, chunks of rubber missing, bent rims, or slipped steel belt are primary issues.

Being not "square on the lugs" is possible but you would have loose lug nuts or, the mating surface between the rim and axle could have something that would not allow the wheel and axle to mate correctly.

In my experience, missing wheel weights or slipped steel belt are the most likely issues for wobble/ vibration at highway speed.

John Stewart
Editor - 4x4Wire.com
Editor - 4x4Voice
Editor - MUIRNet-News
President - BlueRibbon Coalition