This sounds like a classic indication of Boxwood Leafminer infestation. These insect pests of boxwood are very common and many boxwood varieties have a degree of vulnerability to them. Damage can range from an aesthetic nuisance to causing premature defoliation (not widespread on the branch tips, which has other causes, but in the shrub's interior). You can learn more about this insect and what management options you can try in the linked page. The adult leafminers (a small orange-colored gnat) will likely emerge about a month from now, depending on temperature trends. They aren't very long-lived, but they will mate and lay eggs in the leaves to start the next generation of larvae that chew in-between the leaf layers, causing the blistering appearance and orange-blushed color.

Miri