Hello Steve, and welcome!
I incubate eggs in a box on a shelf in the snake room. They're usually about 80-81 degrees. My last clutch started hatching at 64 days.
I have had some take longer, I wouldn't worry about it. Easier said than done, I know.
I took in a clutch that had been incubated at regular room temperature here in the Seattle area, (more mild temps) they took over 100 days to hatch.
I wouldn't be too worried, unless the eggs are looking really bad. Although I have had babies hatch out of bad looking eggs.