John IDed these based on the yellow pores/sacs/?? on the bottom of the leaf. I think there are some visible in the last image. I can post plant images if needed. Are we sure Gagne IDed the plant correctly! :-)

the yellow things... either I've never paid attention to them before or they're not visible to the naked eye. To ID huckleberry I look for brown twigs and shiny, transparent resin dots on the underside of the leaves. The only mention in Gagne's book of galls on huckleberry is another gall that is found on "Vaccinium stamineum, V. spp., and possibly Gaylussacia, according to Osten Sacken (1862)." So apparently either blueberry and huckleberry are similar enough to each other that the midges don't care, or some of the gall describers have trouble telling them apart too!