This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
That's because the Java classes for the Date used by the session where loaded before the change. Java classes are not hot redeployable, just some application/web servers do redeploys and only in some especific dirs.