It sounds like you are getting PVC’s. What does the flagged beats look like? Do you get a stabbing feeling when it mis- beats?

Hey Sean our stories are almost identical, only my ablation was 3 months ago. Like you I have very infrequent strange feeling in my heart beats. My recent visit to my Cardiologist and ECG showed no problems, but as I said to him that is only a snapshot in time. Therefore I want to be able to measure my own ECG when and how I feel something strange or during exercise, and now have the X2.
You are right the squiggles mean nothing to us, however there is a multitude of ECG information at our finger tips. I have spent the weekend learning and studying how to read ECG’s so that I can have just a basic grasp of what I am looking at.
No one can make comment without viewing your ECG, and then at best offer some (non expert) explanation

Ha! its the same here – Ive had PVC’s for over 2 years which is what you are describing here. Just recently I had a fib episode whilst in bed and ended up in hospital with a 170 BPM for 8 hrs until they gave me beta blockers. The PVC’s are a ind of electrical miss fire in the lower left chamber where the muscle is told to contract too early, so it does and then beats harder on the next beat hence the heavy beat or missed beat feeling. I just got the X2 so I could track this over a longer period than 5 mins.