Yes, I had that with the shivers. It only starts for me about 1/2 hour into the session, and as soon as it is over it disappears. It is not uncomfortable, just a bit of a strange sensation. And I am a total wimp about pain and discomfort, so this was really minor. The place where I donate has individual TV screens for each seat, so the time passes fairly quickly. It really is a wonderful thing to do, and I feel really good about myself whenever I do it! Sometimes I specify the donation for someone I or a friend knows, but usually I just donate to the general pool, if that makes any sense!