Abnormal activity after heart surgery

Good morning. We received our device yesterday and are enjoying using it. I do have a question. My husband had open heart surgery three months ago. When he takes an EKG with the device he’s getting feedback of tachycardia or arrhythmia. Mine are normal. We have a call scheduled today with his cardiologist and will bring up these results.
My question is - is it possible he’s getting false positives on his EKG from surgery? He’s had several EKGs since surgery and for the most part they have been normal.