I get them occasionally too. They can be caused by many different issues. One thing you should be careful about is your caffeine intake. Caffeine is the cause of this a lot of times. I drink it quite often, and I get the flutters and heart skipping a beat a lot from it. Stress can do it too. It is uncomfortable, but unless you already have a heart condition it's harmless. Try not to let it get to you. Get in a comfortable position, and if you do drink caffeine try to cut down. It should help.