Your experience is really in order. When you start trading as a newbie, even if it a demo account you are trading on, but it is more on a live account, there is every tendency that the trader will feel a faster heart beating rate. This is as a result of placing an order out of lack of experience and confidence. For me, I believe it is very natural, but with time, the trader will boost up his trading skills and strategy, coupled with experience. As a result, he won't trade with such panic and heart beating faster tendency.