Probably your body's reaction to adrenaline released from the stress. Happens to me all the time when I'm super anxious or panicky. My hands and sometimes whole body shake in the early stages of a panic attack or sometimes even just if I'm super anxious. For me, noticing the shaking and allowing it to happen and not trying to stop it usually works...when I notice it, I tend to relax in to it, and the shaking lessens.