Baby’s sides of head is hotter than rest of body

I’m worried because I don’t know what this means. My baby is 5.5 months. I went to give him a kiss on the forehead and I noticed that the sides of his head is very warm like he has a fever. I just checked his temp and he was at 99.3. What could this mean? He doesn’t show any irritability. He’s eating normally and being playful.