It’s uncomfortable, constant (every few seconds when highly stressed/anxious) and can happen continuously for days/weeks until the stressful situation is over. My doc says they are benign. This started for me a few years ago, never was a anxiety symptom for me before then. 

But why do they happen anyway? How does stress cause whatever is controlling your heart to hiccup? Maybe this is a question for doctors but if anyone has an idea...?