I would go in and have it checked out just to be on the safe side. It really shouldn't be lasting that long I don't think.
Its almost the same feeling as when someone startles you, except constant. Its still doing it and it now 7hours later!
My heart does the same thing and has for years. When I first starte noticing it was when I was in my 20's. I couldn't drink any kind of caffeine what so ever. I also noticed that aspirin bothered it. Through the years, other things trigger the heart pounding feeling such as a breakfast heavy in carbs like pancakes with syrup, msg, fish oil, eating too much... Everyone's body chemistry is so different that one thing that may irritate it might not affect another. Like Michellepetkus, it's probably nothing, but if ANYTHING unusual goes on with your heart, it is best to get it checked out by a reliable cardiololgist.
There are a lot of people who experience what you are feeling on a daily basis and overall their health is fine but it is worth talking to your
GP about and maybe getting a check up if this persists. Take care and let us know how it goes.