He's unlikely to be interested in what you ate for dinner, but there is a small risk that your breath might trigger some reaction. It certainly does in green tree pythons. It's a much smaller risk for ball pythons, but it is probably wise not to allow your pet to roam over your face either way.
Reptiles have a small but real risk of carrying salmonella bacteria in their intestinal tract--since they of course crawl through things when they defecate, you should always treat your reptile as a potential source of this pathogen. Wash your hands after handling him, don't kiss him, and don't let him kiss you, basically.

Most other pets can carry these bacteria as well, by the way--hand washing is always a wise idea. Cats and dogs carry a long list of zoonotic pathogens--reptiles only really carry the one.