Yes, I am post menopausal also. I go thru times where I may have hot flashes often and then times not so much or none. One thing I don't tolerate well anymore is heat, if some place is really warm I can get uncomfortable and almost sick feeling. The days of wearing layers for clothing or sweaters are gone, I am most comfortable in light weight shirts or blouses.
I think your surgery may have been a trigger to have started you back to having some flashes, but do check it out with the dr. I had a awful time in recovery regarding sweating, come to, not totally but enough to hear the nurses say she is wringing wet with sweat and I was some what nauseated, I believe don't know how it can happen that I had a anxiety attack while coming to from the surgery. I don't know if prior to being put out I was so stressed to cause this or what actually set me off, but because of it, they cancelled my first p/t session. Give us a update when you find out the cause of these sweats.