What Causes Heart Palpitations After Taking General Anesthesia For Operation?

I recently had a tonsillectomy. i was given general aneastetic, after the op, in the recovery room, i had a very fast heart rate, i could feel my heart pumping, and got very scared, even the nurse. Why did this happen, and will it happen again, if i should have a nother op. Now 2 months later, i still experience heart palpitations from time to time, but they dont last long, is this due to the op? and should i worry about it?