Is this a poop or regurg?

[Bogertophis]

It was just a general wellness check after I purchased him. That was about two months ago. Think he needs another one?

My point is that a general check up won't reveal very much, if anything. If you're a fairly new keeper, I can understand why you'd do this with a new snake for reassurance, but honestly, it was probably a waste of money unless lab work was done, & something was specifically looked for. Snakes are very stoic patients, & vets can't tell much by looking at them- when you keep one for a while & pay close attention, you can often tell something is wrong, but a vet will still "see" nothing. It's often up to us to take good notes, to help a vet figure out how & what to treat. A "team effort".

Did he come from a private party (breeder?) or a pet store? You haven't had him very long...re-homing is stressful (so are pet-stores, & they often expose healthy animals to sick ones) so the best thing to do with a new snake (FYI) is to let them settle in for several+ weeks, just eating & sleeping, to keep their immune system functioning at it's best, & minimize the chance that something they've been previously exposed to will affect them (ie. make them sick). Not much different from humans, btw.

The vet you took him to...was a specialist with snakes & other exotics, I hope?