I had one of my females regurgitate a rat, I followed up the next day with another and she was OK. I figured she may have ingested coconut husk substrate along with the rat, it was a regurge probably an hour after feeding.
I have another ball python I've been struggling with, he is a male Albino Pied. He regurgitated almost all of his rats in the last couple months. I'm guessing since it's breeding season he is just getting moved around too much and weekend feedings followed by a breeding rotation is just too much for him. It's also possible that his double recessive genes are making him susceptible to it as well. This week I decided to give him an extra day before moving him to a female and I made sure to move him as little as possible when moving to the female tub. The funny thing is that he regures several days after the feeding so most of the rat is digested. He seems to be getting a bit weak and thin so I keep feeding him hoping that minimal handling will do the trick. If he regurges a couple more times I may just take him out of the female rotation for a month or so and not feed him at all for awhile.