I see some potential for abuse in this. What if you step on a mine and just undo it? What if you walk into LoS of unaware enemy and undo it, will they forget about it? Player would be able walk around the corner (in combat) to reveal unexplored area, and then undo the movement and keeping all movement/action points. You can already check enemy positions in explored area just by hovering mouse over traversable tiles, as pathfinding line reveals occupied squares. Knowing the exact positions every single turn is huge, and I think this mechanic is most likely not intended to work like that. Ability to undo last movement will make it even worse.
To avoid missclicks I suggest to take it slow.