Hey read your post.....i doubt very very much that your heart will stop beating just because you are throwing an extra beat here and there it would take alot more than that to shut down the pump that runs your body so i would relax a little. It is so common to feel when its about to happen trust me....sometimes you get that funny thing up in your neck area and then that jump feeling and then back to normal and when you feel it at nite that is the time when most of us feel everything because there are no distractions, sound, activity and we notice absolutely everything including things that go bump in the nite as the saying goes meaning people walking, dogs barking, whatever. Distractions. I don't think that i would worry but i would definately stay away from anything that is caffeine based or sugar based so your heart doesn't speed causing the extra beat to jump out. If concerned you can always just pay the 50.00 and have a heart doc listen to it but i seriously wouldn't be too worried but if you do get any other symtoms with that make the call.....good luck
Consider yourself lucky it doesn't happen several times a day. Likely a premature ventricle contraction (PVC), very common and very benign in most cases. But if you can't stop worrying, check it out with your doctor. The downside, if you heart isn't doing it often, your doctor will not likely be able to observe it.
Again, stop worrying. You're just fine, that's what I think.