No, regurgitating is not normal for a snake.
Where are you measuring your warm-side temperature, and do you have a thermostat for your heat mat? Reducing the warm side temperature to 85 degrees Fahrenheit (so that your snake is more likely to use it) may help.
It sounds like you've adopted quite a long time between feeds; is this because she's regurging (I wouldn't feed for fourteen days after a regurge, and I'd be adding Reptiboost or Avipro to the water in between to help renew her gut flora) or because this was how you were instructed to feed her?
I would bag up the regurge and refrigerate it; take it to a vet to have it checked for parasites, as this could cause repetitive regurge.
"My bum has been a bum for a very long time, but that does n't mean I have to listen to what it says."
- Terry Pratchett, Fifth Elephant