I am 57 woman..in good health. 11--120 to 70 bp..colestrol around 180 and low resting heart rate 405-66,I work out regularly, am a cycling..run up 3 flights of stairs at work every day and walk at breaks at work.  I also take exersize classes.  I eat well ..low fat / limited meat/poultry.  sometimes when i am laying down watching tv my heart flutters...it always has...but the last week i notice it more.it only happens in the evening when I am watching tv...
You are in good shape. You feel when you are not busy. Appear to be harmless. But if you want to clarify get 2 D echo, T/t and 24 hr Holder Monitor. In meantime don't worry.