I have had this happen in the middle of the night. My thoughts are that are temperature is regulated by our hypothalamus. It also is responsible for the release of many of our hormones.
During sleep, our core temperature is regulated by the brain. If your temperature goes too high, your blood vessels dilate causing the redness you experienced. Sometimes your brain may not regulate properly and cause your temperature to rise at a certain time. If so, your body may respond by elevating the heart rate, as it does when you get a fever. It does this to reduce heat by tissue perfusion.
I don't think it's anything to worry about, but I think if you make sure you are properly hydrated before bed and you're not dressed too warmly, you shouldn't have this happen often.
it happens to me too sometimes (hullo Rita again) and I get up and take a couple of mg Valpam and splash my face with cold water. Also drink a glass of water. Back to bed and I prop myself up with an extra pillow for a while and it passes and I go back to sleep.
I've been having these things for years, and there re no real answers. Don't worry about it - tell yourself you're too hot, cool down and it won't happen again.