Yup... that moment when you lift finger off shutter button, camera stops tracking. And the moment you press it half way, camera starts to track. But because of this short break in between, it's all like you would start tracking from beginning, which you actually do. So it takes some time, before camera calculates everything and tracking is long enough to have sharp photo again. I agree this interval is short, but sometimes it's long enough for you to miss whole action... or have it out of focus.