Orientation is locked even though lock is off
I just got a new iPad Air 2 in September. Every once in a while, when I open the case to use the device, the orientation is locked, usually on landscape when I want to use it in portrait. I have orientation lock off. When I'm not using it, I have it leaning upright against a table. The only fix I've been able to come up with is to turn my iPad off and turn it back on. Is there a better fix? What could be causing this? I'm sometimes in landscape mode when I close the case but it's not always locked when I open it after that.
iPad Air, iOS 10.1.1, 2nd generation, WiFi only