They're being changed as part of the EoFF Classic Banner Competition we had awhile back.

The specific reason being:

Quote Originally Posted by Loony BoB View Post
After a lengthy debate we decided that, as none of the banners were concrete favourites in any way and as Leeza's banner was still a firm favourite to remain instead of having a new banner, each of the finalists will have 5-7 days sitting atop the forums before Leeza's banner returns.