Argh, that is really strange. One thing came to my mind just now. If you visit your profile, in the very left frame you get the options:
-Profile Info
-Modify Profile
-Actions
The second menu "Modify Profile" contains "Look and Layout Preferences".
My current theme is switched to "A Mark In Time 1.0_Black" and the new logo shows up. Maybe you are using an alternative layout?!
