A few times now, inconsistently. Only my face and head became very warm not in the neck or body. Became red in face, others could see?

It could be Flushing. If you have this symptom for more than a few weeks(like for a few months) then you should go see a physician as you will need a physical examination and tests to find the cause of these flushes and skin redness. There are a few rare medical conditions which can produce excess of hormones(like serotonin) leading to symptoms like you have. Good luck. Give us some follow up.