This is something which I suggest that you get checked out properly. A condition known as Short QT syndrome has only recently been identified. It is a congenital condition, meaning that it may affect many people in the same family. This condition can predispose to "funny" heart rhythms, some of them potentially dangerous. Is there a history of heart problems in your family?
This post is not meant to alarm you. It is most likely nothing. I just recommend that you seek a proper medical opinion on this one, not just the advice of PPRuNers...