Maybe....maybe not. I am a life-long outdoor guy, runner, cyclist, snowshoer, always ate well, not an unusual amount of stress.....until I fibrillated at the end of a 10 km maintenance run. It wasn't a particularly arduous or unusual run, it wasn't hot....but I began to feel weakness in my legs, they got heavy suddenly, and my breathing changed. An hour later the ER told me I had paroxysmal AF. And that was just the start. I ended up needed two ablations of my pulmonary vein ostia in order to stop it.

It was obstructive sleep apnea. It was the very last of many tests I was subjected to. An over night polysomnography showed I have 'severe obstructive sleep apnea'. Who knew!!

Doctors are told of, and soon enough encounter, 'holiday heart' where a young person has overindulged on a weekend bender (happens, right?) and they present in their local ER with a thumping and irregular heart rhythm. Soon, the heart returns to normal rhythm and that's the end of it...after fluids and rest.

So, your arrhythmia has an indeterminate origin as of now. It may be a one 'n done, or it may return in a few hours or days, weeks, or months. If it returns, and for no apparent reason or stress, then it suggests you have commenced a progressive history with a tachyarrhythmia. You would want to see a cardiologist soon and get a referral to an electrophysiologist (EP), a heart rhythm specialist.

I'm sure you understand that you should hope to, and try to, duplicate any possible circumstances that might have led to the episode while you are being monitored. If you look back and can think of something unusual, and it wouldn't mean endangering yourself, it might be worth trying to get the arrhythmia to repeat.