Didn't you say in another thread that you had handled him for 30 minutes prior to the regurge? (correct me if I'm wrong) That's a pretty long time and could be stressful. I'd personally recommend not handling for so long at once even after you start handling again, but that can really stress out a snake especially if it's prone to being a bit nervous or jumpy.
Like everyone else has said though, you can't tell what exactly caused the regurge, so you have to use the process of elimination (in this case, eliminating handling/husbandry stress) to figure out what caused it.