Answer: Pines undergo a natural seasonal needle drop where the oldest needs turn yellow and fall off each year in the autumn. So, as long as the newest needles at the tips of the branches are still green, I think what you are seeing is probably normal. Since it is new, you might want to consult with your retailer as well. They might appreciate a photo of the overall plant so they can see the pattern of the discoloration.
This tree will need some special protection during the winter because it is in a container. You will need to insulate the roots as much as you can, such as by heaping mulch over and around the container (do not let it touch the bark however). Make sure the soil is slightly damp any time it is not frozen. If the rooftop is windy, you may also want to provide a windbreak especially during the winter months. Do not fertilize it until spring.
Good luck with your pine!
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