Apple Watch notification for AF but none on ECG?

I've had my Apple Watch 4 months. I've done my ECG about 10 times since then, normally when I feel palpitations which people have said look like premature atrial contractions - harmless. But absolutely no atrial fibrillation according to the watch every time I do an ECG.

Today my watch notified me that I have been in atrial fibrillation "8% of the time" assuming since I've had the watch. I'm thinking probably should see a doctor or is this known to not be accurate? I'm not sure a doctors going to accept my watch told me to, as a reason for my visit.