If it had just fed, the pet store should have asked if you'd be willing to come back in a day or two to pick it up, to allow it time to digest. I imagine the stress from moving from the pet store to your home was enough to cause the re-gurge. Don't attempt to feed for about 2 weeks, as it needs time to re-build its stomach flora.
If you experience another regurgitation, try to take a fecal sample into your vet to test for internal parasites.
Pretty snake!