Yes, they are anything OTHER than sinus (normal) rhythm & often nothing of concern. Ask your doctor or cardiologist, to pinch & expand the graph on these markers, so they can analyse.
Remember too, that FRONTIER X2 has a disclaimer, reminding you that this is not a medical diagnostic tool.

If I’m not mistaken you can do one time session with Frontier and maybe they look at it and point you in right direction. This is their device they can tell you. This is not a medical device. I would just schedule ECG with doctors office and clear matters up. You don’t need to pinch and zoom to see it either. I would say what I see but it would be moderated, because this is not medical device.