Vibrating/shaky feeling

Today, while working with a patient, I was personally working on maintaining relaxation whole holding on to the 6 harmonies. First, this was more difficult. Lol. I was able to keep the shoulder/hip better than the elbow/knee. And the hand/foot just wasn't there in motion. It's been about thirty minutes since I ended the training and I've had a shakiness/vibrating feeling inside my body. I'm not overtly shaking not do I feel bad. What is this? Is it normal?