And needlessly worrying someone can be just as wreckless but you are right it could be anything and anyone with any health issue that causes them concern should seek out their doctor.. That said, this is a patient forum not a doctor forum.
I don't think you can give a true diagnosis based off of "beat.beat.beat.beat...beat....beat...beat.beat.beat". This could be any number of arrhythmias, like sinus pause, sleep apnea, Atrioventricular Block (1st degree, 2nd degree (types I or II)...), etc.
And yes, there may not be anything to worry about, but then again, I triaged a patient whose nurse told him the same thing, "Don't worry, sinus arrhythmias are normal, everyone has them to some degree"; he had 3rd degree av block and now has a pacemaker. You shouldn't google advice and then throw it out there like it's the absolute truth without some medical knowledge and, at the very least, a look at an EKG.
You could be having short runs of VT or non-sustained SVT. I've had it myself. This is beyond normal changes in rhythm that occurs with respiration. Something to keep an eye on and report to your physician.
I have arrhythmia problems anyway and occasionally I get what I call "wacky tachy." My heart will have a few normal beats, jump to a quick step of 150 bpm or so, back to normal and back up again. That's all part of my PSVT. For me it only lasts a minute or so and then my heart settles into its usual slow rhythm. It doesn't seem to harm me in any way. Just a variation of my PSVT.
Its called Sinus Arrhythmia and everyone has it to some degree. Your heart rate is different when you inhale as opposed to when you exhale. Inhaling speeds it up while exhaling slows it down. It was likely more prounounced for you at that time due to some anxiety from the unpleasant dream. It is nothing to worry about.