You also had the option of changinging the header size.
What you are doing sounds fine though.
For future reference.....
One thing I have seen done is to modify the header on the inside of the house with an LVL. Removing one of the layers of 2xwhatever you have and notching the king stud to accept the LVL. This way you do not have to mess around with the exterior, and this will carry the weight of a one story home.
I would never have returned the door either.Have you ever seen the look you get at the service counter!!
Good luck with your door.