When there's not enough space above the button, the entries switch order. Where you would have moved up 5 entries for the NLA-Editor, now you move 5 down. Is there a reason for that?
The reason would be considered consistency. As menus are intended to be a mouse driven UI element, having the same option two steps from the mouse click is considered consistent. This changes when a user uses keyboard navigation as the direction to move changes depending on the location the menu starts.
use_directional_menus option defines which order menus are drawn. When disabled menu items will always be in the same order, top to bottom.
This option isn't made visible to the user, so it needs to be set manually. Using blender's Python Console type in
C.user_preferences.view.use_directional_menus = False
If you want this option to always be set, set the option and then in preferences click Save User Settings
Just another UI design as you are maybe used to. In both of them you move 5 steps from your first click. For me this is also more natural.