I wonder if it is tied to the length of a particular game session (not turns, but time since the game started/loaded). I've seen variations in how much of the panel fails to slide into view, sometimes less than 1/4, sometimes maybe 2/3. I've been interpreting it as a bug with the feature of helping me shrug off just-one-more-turn.
I have a screen cap if a dev reads this and would find it helpful.