I take Tegretol and do occasionally get palpitations. I'd not linked the two before but maybe there is a connection. Having checked the long, scary list of possible side effects, "changes in heart rate" is mentioned. They also warn against taking the med if you suffer from a serious heart condition.
Definitely talk to your doctor as soon as you can if you're worried. Heart problems don't fall under the category of a "little thing." And doctors are there to be bugged.