Low heart rate after surgery

Hi! I was recently diagnosed with stage 1a lung cancer, and had a robotic right lower lobectomy in April. I am so grateful to have it removed, with no other spread. However, since then I've been experiencing periodic bradycardia, with my daytime heart rate averaging in the low 50s, ofen dipping into the 40s. My cardiologist believed it could be a result of my beta blocker (25mg metoprolol, taken for hypertension), so we stopped it and began losartan. I had been prescribed gabapentin for surgical pain, which was tapered and stopped as of 10 days ago. Despite discontinuing the metoprolol, the low heart rate continues, and an EKG from last week showed a mild sinus pause. I do have some nerve irritation post surgery that causes a dry cough, and was thinking there could also be some vagal nerve irritation as well. Will do a holter monitor next week if things don't improve post-medication change. Was wondering if anyone has had anything similar, or have any insights?