It's kind of a yes and no thing. They should feel warm to the touch because the skin is thinner and you can feel the heat from the blood flowing easier in the ears. However overly hot is not normal. Make it a habit of petting the ears and knowing what is a normal temperature for your buns ears. There should be other signs and symptoms if your bun was not feeling well. Tooth grinding, lethargy, not eating, strange poops, odd behavior, etc.