Heating pad damage?

I am 2 months post op from a bikini cut laparotomy. I have been having a lot of abdominal pain from a tubal infection post hsg so I put a heating pad on my abdomen. My incision scar is now super super red. The skin around is normal color, but the scar is soooo red. I am still numb so it may have been too hot and I didn't notice, or its just new skin and reacts more? Should I be worried? Anyone do this before?