I can make it happen to mine every time. Just let the iPad sit in rest mode for about 10 minutes, and then wake it using the home button. Waking it with the home button takes a second or two longer than usual now since 8.4 was installed. If I notice there's a lag when it wakes, it's 100 percent of the time accompanied with the screen orientation lock bug. If you do everything I described except use the lock button instead of the home button to wake it, 100 percent of the time you'll have no screen orientation problem. I hope they fix this quickly.
Mine does it with the lock button. It's done it twice now.