Hi JimR,
I too have these odd ectopic heartbeats/palpitations. In fact, about 5% of my total beat count are ectopic heart beats. Last year, on my initital class 1 medical, they picked up these palpitationns on an ECG. Following a positive exerise ECG and echo, I did a 24 hour holter which revealed 16% ectopic heart beats. We found out that my excessive tea consumption (2 litres a day!) caused them. So I gave up the tea as well as any other stimulant such as coffee, coke etc. and redid the 24 hour holter. On the second holter they have decreased to 5% which is a great reduction and no problem for the medical class 1. I too took magnesium oxide pills. I doubt that they helped much though..
Heart palpitations often have a psychological reason as well. Stress, excitement and misery can make them worse.
What one should also keep in mind is that basically everyone has them. Some feel them (like you) and some don't (like me). As long as the heart is strutally healthy and they don't appear too often, it should be no problem. Cut out coffee, tea and reduce stress. This might help!
Best regards