This is strange. It's doing the same thing to me when I'm attempting to do an admin override on it. It will show as changed, but when I refresh the page, it's reverting to 0001-01-01. This happens no matter what I put in there (I tried 1970-01-01 and 1776-07-04 just to see if it would take, and it didn't).
Did you intentionally put anything else in besides 2002-05-28 at any point?