This is one of the action bugs the devs know about but they struggle to find the cause http://forums.obsidian.net/topic/76085-grimoire-slam-says-always-already-activated/
It is intended that you can change your opinion in the end. You will get six choices, not only four. I would suggest to stick to the right choice and bear the wrath of Hylea because the kind of punishment will be probably unexpected.