First, let me say reading view is pretty cool. The screen space on my 13" MacBook is limited (to say the least), and I have often wanted a quick and easy way to go full screen to read something and then go back. So I really like this feature.
Most of the time when I go from normal to full, everything is good. The information displayed in both views is the same. But sometimes, particularly for Bibles, the normal view and the reading view are out of sync.
For example, I am working in Eph 4 now, so I have the NET Bible open to Eph 4:22:

But in the reading view, it's actually displaying Eph 5:6:
