Antimatter and matter fall at the same rate. Well, within 3%.

Let's say I'm a mad scientist*. I have a ball of antimatter and a ball of matter, which I have carefully measured out atom by atom to be exactly the same mass in my Matter-Antimatter Doomsday Device Maker. I then hold them both over the ground at exactly the same height, and then let them go.

Will they hit at the same time? Or is there some fundamental property of antimatter that makes it respond to gravity differently than normal matter?