I almost always use my iPad 3 in landscape mode...95% of the time easily, it I am not seeing this behavior. The fact that you see it on both devices is very odd.
Do you have any apps in common on both devices? I suppose that there is a chance that a corrupt app could be causing your problem. Why don't you try closing all apps on the Air, then reboot it and see of that helps. If it works, try the same thing on the iPad 3.
Double tap the home button and you will see apps lined up going left to right across the screen. Swipe "up" on all of the app thumbnails to close them.
Reboot the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider if it appears on the screen - let go of the buttons. Let the iPad start up.