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.