Yeah, those are cardiac arrhythmias. But I wouldn't worry too much--cardiac arrhythmias are actually pretty common. The kind I have is called "premature ventricular contraction" and they are actually experienced by most people occasionally. They are what's happening when it feels like your heart is "skipping a beat". For me, they just happened often enough for it to become troublesome, and I would occasionally get dizzy; and they happened even when I completely stopped taking all stimulants, including caffeine; so I went to the doctor and got a heart monitor put on for a couple of days, and they saw the abnormal ECG and recommended beta blockers. Since then I only have those skipped-beat sensations occasionally, which seems to be normal, and no longer have problems with dizziness.
If they worry you, talk to the doc at your next checkup and get him/her to figure out whether they are normal glitches or whether they might eventually cause problems.