This is not uncommon, nor a reason to worry. As long as she is maintaining her weight, she's probably a totally normal, healthy KSB. When I've had KSBs go off feed, I typically cut back how frequently I offer them food until they start back up again. I've heard of large females that would go nearly a year without eating (but I can't back that up, as I haven't actually witnessed this, and it would be a terrible experiment.)

Maybe someone else has some ideas or experience with handling and snakes off feed, but I personally have a sort of superstition with any animals that have gone off feed, and I NEVER interact with them. I let them be, and only refill water/spot clean cages.