I am surprised they didn't send some "packing peanuts" (roosters). Most hatcheries won't ship that few chicks because of the problems like you had - day old chicks need more warmth than what 3 or 4 chicks can make. Some hatcheries will tell you that if you order under a certain amount, then you will get roosters as fillers or you have to purchase insurance if you don't want the added roosters.
Yep, I'm surprised to hear that they only shipped 4 chicks as most hatcheries won't for this very reason...