My ds started Propranolol at 3 weeks and was in the PICU b/c his H is in his airway. So he was on monitoring. I never saw a pause at his first visit or any after where monitoring was done. However I am just one. So, the health care team see patterns where we may not. That being said, might not hurt to just consult a pedi cardiologist. Your primary pedi might do it for you as a phone consult to start with just to see if you should be seen.
Hope that is helpful
Blessed Mom 2010