Your snake probably had just been sitting there waiting for a meal as snakes do and a nice warm hand moves into its face, not really a surprise it bit you imo. There's also no reason whatsoever to introduce your python to your puppy and I would recommend against it for the safety of both. It might be the extra noise, strange smell and movement/changes with the new pup that have it on edge, I'd keep the puppy out of the snakes area-assuming they are separate rooms?