I wonder if they made this move because everyone still calls them the Lite, but 93.9 FM in Chicago hasn't officially been known as the Lite for many years now. This weekend they announced that they are bringing back the old name. Robert Feder has the details.
When I worked at WJMK in the 90s we went through the same thing. Before I got there it was known as Magic 104.3. It was changed to Oldies 104.3 just before I started working there. After calling it Oldies for about five years, we decided that everyone was still calling it Magic, so screw it, we once again became Magic 104.3.
It's a branding thing.