It's an annoying bug. I've had this problem occur post-launch with Madora. She had not moved for several turns, and the only debuff she had on her was "wet". And yet it cost her 5 AP to swing her weapon (instead of 4) from a stationary position for most of the battle.
![[Linked Image]](https://farm4.staticflickr.com/3912/14632182111_3343fb8a61_b.jpg)
As you can see, the cost on the weapon is 4 AP, but the game is charging me 5 AP instead (and that character and elemental had not moved for a few turns). I've had it happen to me several times on different melee characters for no apparent reason.