You most likely have the same thing I have.
Clinically, it's a benign tremor. Mental and physical stress will temporarily worsen the shakes as will undue stress caused from drug use.
You can get meds to take daily to stop it, I opted not to; I know many people with the same problem. It's easier to just deal with it.
I got over being embarrassed from people telling me years ago that my hands were shaking. At rest, it's a very mild tremor and not it's not parkinsons and does not lead to it.
I tried accupuncture and a course of herbs over the course of a month once and that worked really well actually.
Anyway, if it doesn't impede your life any real way i wouldnt worry too much about it, it's not uncommon.