Is she sitting directly on the heat pad? The belly looks a little dingy, but not like it's the start of a burn to me. As someone who keeps her snakes with a usual high temp of 95 or so, I know those temps aren't warm enough to cause a burn unless the snake is sitting directly on the heat and not moving. Make sure she's not directly touching the pad, fluff up the bedding, and she should be fine. You may want to look into methods to increase the ambient temps so that she doesn't feel the need to huddle on the heat pad for long enough periods of time to burn herself.

-Jen