You'd thing wrong. The issue is panels refresh top to bottom, and in this case Top and Bottom in Landscape Mode is Left and Right in Portrait Mode. This is why you see the left side refreshing at a different rate than the right when in portrait mode. It's a sync issue that should be fixable with a firmware update, but the disappointing this is it wouldn't have been a problem at all had Apple not cheaped out and went 60hz instead of 120 on these panels.I think if it would be a hardware issue you should see it in both orientations. Of course it is unfortunate and they should definitley fix it but I still love that iPad Mini
But of course, Cook gotta Cook and pinch those pennies on his premium devices.