just a little problem in outliner

hi all, i’ve a very little problem: i use a lot outliner when animating, when i set a key for an object (even if for mistake) in outliner blender sets the animation icon for that object. removing keys, actions, and all of that mistake, that icon remains in the outliner… empty. anyone knows a trick to purge that animation icon (and the relative tree field) if unused? thanks for any suggestion.