Having vended at many shows and bought countless snakes from them as well, let me let you in a little show secret, low temps. Reptile shows are kept a comfetable temp for the human guests, not the reptile products. Normal room temp in those places is around 72-76. The snakes are sluggish at these temps. Don't worry, the couple of days that they are kept at these lower temps don't harm the snake over the long term, they just have the ability to temperarily calm all but the most aggressive of beasts. You get the snake home, get its temp up to the point where it gets its metabolism moving again and the snakes true colors may come out. Also hatchling balls are more instinctively more aggressive. Rememver that everything in their natural environment is a threat. Just keep trying with it and they normally calm down over time.
Also, your temps are great. Your snake as a wide range of temps to choose from.