oh, don't worry, hun. my girls aren't here yet, but i know Chard packs them SUPER well. when i got Sniper, the night time temps were in the upper 40's, but his baggy was still warm, the heat pack was still warm, and he had, like.... wrapped them in paper, layered the box with thick padding, and lined the outside of the box in Styrofoam. i'm sure your boy will be fine.
but, yes. i think PewPewPew's story's proof of how shipping fish in cold temps can go wrong. D: i'm SO upset about that! she was super excited about getting him, too. if you DO get a fish shipped, if you can, do it Express. and try to avoid getting them around this time. x-x mail's super slow, with x-mas being next week.