The weather outside when I was enroute to home was in the 30's, and by then I was on Advil which for me does drop my body temperature half a degree. I agree with Izzy (when don't I?) that taking your temperature is a good idea, if for no reason other than to reassure yourself there is not problem with fever. I used very light nightgowns when I was not actually outside the house. You are doing a lot of healing, and your blood vessels are bringing the body's healing agents to you on a rapid basis. This means that surface blood vessels are a bit more active.
Congrats on the surgery.