Same here. For about the last 4 or 5 weeks. I am on minimal HRT, had a hysterectomy 25 years ago in my 30's.

It first hits at about 3 am, and then hits again at about 6 am. I can't figure out what is doing it. It's like a heater gets turned on for a couple of minutes, and then it's gone. It isn't like a real hot flash at all.