First there is a difference between an animal spitting a prey back out immediately and a regurgitation, in this case it is a regurgitation which means it need to be addressed as it can become a serious issue.

First do not feed your BP for the next two weeks (this is part of the recovery)

Next regurgitation can be due for several reason

Stress, over-sized prey, low temps, not properly thawed feeder (if fed f/t), and internal parasites.

If the animal regurgitate again at the next feeding (2 weeks from this one) I would highly suggest to get the animal to a vet and have a fecal done.