Chances are you are having what is called a PVC or a PAC
PVC=Premature Ventricular Contraction
PAC=Premature Atrial Contraction
They are totally harmless, but they can be very unsettling.
It is when 1 of the 4 chambers of the heart beats out of sequence. While it feels like a skipped beat, it is actually an extra-beat and then a pause
Everybody has them, but things like lack of sleep, bad eating, and stress
can cause them to increase.
Also, once you get stressed out about them, you start to notice them more which makes it seem like you're having them more often, when in actuality, you're just listening for them and focusing on it a lot more.
The only way to confirm that this is what it is is to wear a 24-hour holter monitor
If your EKG is fine, and you are under 50, I wouldn't worry about it.