Is Private Browsing broken in Safari 5.1.4?
There was a bug that prevented cookies set begore going into safe mode from working again after the safe period had ended. 

Imagine a truck with four wheel drive and when you were done and switched back to two wheel mode. It would be a problem if the indicators said two wheel but four was still engaged.

This text you quoted indicates the getting out of safe mode was tweaked so more things work again post safe mode.