Honestly, I wouldn't sweat a one-off that might have been due to an adrenergic reaction. If it repeats when NOT under any duress in the next three months, that might be an indication that something has been developing and is gaining ground, or simply that you have the odd short-lived glitch. Some with arrhythmias of a kind might kill for a heart that is 'good' 97% of the time. If it repeats in the future when you are once again under a thumb, maybe that's the new reality and you should try to limit stressors.

Six seconds is not long. Many with fibrillation or SVT eventually seek help because they are getting longer sessions and more frequently. I would counsel you to relax, shrug it off as early as you can let it go, and try to limit undue/unnecessary stress. I would trust my spidey sense when/if the frequency begins to creep up and the events seem to go into minutes. You're not there.