If it was me, I would call the vet and explain it to him/her exactly as you have here. Tell them what your concern is, and ask their advice whether or not you should bring him in. Ask for other symptoms that you should be aware of, and tell them that you are ready to head out for a trip.

Please keep us informed. We will keep you and the Dukester in our thoughts, and I hope you have a wonderful worry-free road trip!!