Animation rotation property with right angle curve

Hi,

I'm trying to combine a sprite-atlas based animation with a transform based animation. I have a character that is animated with a sprite-atlas, and during the animation the position of the character's face jumps from place to place (part of the sprite, not separate object). In addition to the character, I sometimes want to display a blood splash on the character's face, so I added the blood splash sprite, and control the blood splash's position and rotation with an animation curve, so that it always moves with the character's face.

I set up the animator and recorded the position/rotation, and then set the curves to a straight angle, so that it changes over a single frame. It works well for position, rotation however ignores my curve and changes the rotation over a longer period of time, making it look weird when the face moves in a single frame and the blood splash moving gradually.

You can see in the screenshot, that although according to the curve the rotation should be 0, it is actually 9.8, slowly rising to 15.

Any ideas?