The feeling is almost certainly attributable to the propofol or maybe the little bit of fentanyl they sometimes also use in addition to the propofol. You should feel nothing unusual when your heart is happily beating in NSR.

I know a woman on affibers.org who claims to have had over 50 cardioversions. She's not a nut case, but her heart is. She's about the strongest person I know...period...for what she has endured. So, don't sweat having cardioversions, even if they only buy you a month of peace. It's better than the alternative because a heart in AF is an ailing heart that will begin to remodel itself and bring on more intractable arrhythmia and even mitral valve prolapse or heart failure. IOW, the less time you are fibrillating, the better off you'll be in the long run.

That said, any time before you progress (and you almost certainly WILL progress...) to more advanced forms of AF, they being persistent and permanent, you should be in line for catheter ablation. It may sound daunting, especially if you haven't educated yourself about it for any reason, but it's not much more complicated than an endoscopy with some polyp removal and such. The manipulation of the catheter is routine, what it does has been practiced for decades now...it's just day surgery! But it will stop your inclination to go into AF now and then, if it works, and you will have decades of bliss ahead of you. Put it off until your heart begins to give you signs of progression, or until you get scared enough to do it, and you make the job of detecting and isolating the re-entrant foci of the unwanted/extra signals that much more difficult...meaning harder...meaning the risk of it not working completely rises. Make up your mind early and find a really good, busy, highly regarded, electrophysiologist, meet him/her, and get into line.