I have the same thing for 40 years. Finally after many many tests, they saw it happen on my EKG.. mine is called PVC'S premature ventricle contractions. My heart has a extra beat from time to time. It takes my breath away. It feels like a flutter in my chest.. Cardiologist will help
About five years ago I was having rapid heartbeats off and on. My primary doctor heard them one day and sent me to a cardiologist. He listened to my heart and told me I had an occasional skip and not to worry about it because a lot of people do. About a year later my primary doctor heard them again and sent me back to that doctor. He asked me why I was back there and I told him my doctor didn't like the sound of my heart. He dismissed it, told me I had a skip and sent me home. shortly after that I had three TIA's (mini strokes.) I went to another cardiologist and was in full blown AFIB. If the 1st cardiologist would have put a 48 hour Holter Monitor on me, they may have found it sooner. I hope this helps.
Well, age itself is a risk factor for many diseases, so yeah, as time marches on... but you know that. ;-)
However, if you have had fairly recent EKGs and all that other stuff, and if you live healthily (diet, exercise, weight, etc), you're probably still in 'benign' territory. As you've probably read over and over again, ectopic beats in a normal heart are not associated with a shorter life.
As to flareups, I've experienced them for decades now--long periods of nothing, and then a sudden burst of PVCs. The cause of benign ectopics is still unknown, so we just have to learn to roll with changes like these.