I can see if it was a mild year like the last 2 but we’ve actually had snow this year. I don’t think it’s uncommon, but hubby and I have never seen one in winter.I would say we see Robins in the winter here on occasion for the last 10 years or so. About 15 years ago we were going for a walk in a local woods that is open for the public. It was in the middle of winter. We saw a flock of Robins that had to be in the hundreds! Never saw anything like that before or after that! I sure wish it was a sign of spring! I think confusion as you said is more likely!