So he's eaten 3 times for you? IF he's a reliable eater & IF you can maintain his "travel tub" to closely approximate his home (temp. & privacy-wise) once you get there, considering gas prices & hassle of making 2 trips, I'd lean towards taking him, BUT ONLY IF he has a discernable issue, which apparently he doesn't.I know you're a worrier & ultimately the decision is yours, but vet visits are stressful anyway, there isn't much the vet can "see" (snakes are very stoic) and personally, I don't advise "routine check-ups" for asymptomatic snakes.
What I'd do instead is explain to the vet you'd like to avoid the stress (for the snake) of a trip at this time (as your snake appears healthy) but just for peace of mind, you'd like to have his stool checked- will he do that? However, it does have to be fresh...so there's that too.Ask them how fresh would still be useful, if you go this route?
Remember that stress can lower the functioning of a snake's immune system- & he's still new with you. Assuming this trip doesn't adversely affect his appetite, it still might not be harmless.