Others will chime in I’m sure. But in my circumstance with our rabbit, yes, it was normal. Sometimes her ears would be very hot, other times they would be downright cold. The ears are their primary way of controlling their body temperature (I believe that is stated correctly). They dissipate excess heat by dilating the blood vessels in their ears which makes the ears very warm.  Other times her ears would be very cold meaning the blood vessels naturally constricted accordingly. That was our experience with our rabbit. It was a strange thing to notice for sure. Because the differences could be extreme. But it seemed to be a very natural thing, like breathing.  And it seemed to be independent of the temperature in the house, because that was kept relatively consistent.

It depends. How long have you had him? If the weather is colder or he is in a relaxed resting position then it’s more likely that his ears will be cooler. Are there any other abnormal behaviours? Is he hunching or pressing his ears against his body etc.? Eating/drinking/pooping normally?

Yes, I was commenting on the sometimes cold ears and usually hot. I was assuming there isn’t any behavior change associated with the changing ear temperature. If his behavior is significantly different as well then there could be something going on. Is his behavior different like kurottabun asked?

Well if he is eating, drinking, and pooping normally, then he is probably A-ok. His ears will probably vary in temperature from time to time.