Hello,

The terminal shoot may have been chewed by the western spruce budworm earlier this spring. The good news is that the tree has set both lateral and terminal buds. These insects are usually kept under control by natural predators and climate. 

Continue to invest in keeping the tree healthy and stress-free with regular water (including in fall and winter). This insect usually doesn't require the use of insecticides, except in forest situations where it is affecting many trees. 

This also could be from environmental things too and can happen, especially if it's a newly planted tree.

Thanks. One of the reasons I was worried is that I have three of these, and this was the only one affected.