When you rotate a layout containing a button, the button doesn't rotate correctly. It either shouldn't rotate at all, or (preferably) should rotate like all other objects, not just sort of rotate and resize. The problem is demonstrated in the following .capx:
(Edit) Just repeatedly click the button until the layout has rotated at least 180 degrees to get the full effect.
This is a fairly low priority problem. The workaround is to not use buttons on a rotating layout, but instead create your own pretty sprite-based buttons!