Did you look at the attached screenshot? It clearly shows the Date as December 31st at 11:05. That is the clock on the phone when it is locked.
After unlocking the phone and going to the calendar application, it showed april 1st.
Today, My wife's Iphone 4S just showed the date was March 31st at 8:46 PM.
2 phones showing the wrong date/time on 2 differnet days.
Also, my wife has an ipad. She was getting text messages on the ipad on sunday but not the iphone when the date/time was not correct on the iphone. After restarting the phone and the date/time was correct, then he started getting texts on both the ipad and iphone.