Is it normal for the top of my baby's penis head to be red?

No: He likely has a small area of balanitis, qhite common around the urinary opening (meatitis) ; due to delicate head of penis rubbing agaist diaper (more common with cloth diapers). Best to leave diaper off when this occurs, color should return to normal within a few hours. Can drape crib with towels to contain urine. Bacitracin can be used. Try to avoid meatal stenosis (narrowing) a complication.