on the symmetric space for $g_2$, there exist various submanifolds $g_d$ corresponding to the stabilizer of a norm $d$ vector. we show that when a suitable automorphic form is integrated against the $g_d$, the resulting numbers assemble to give a half-integral weight classical modular form. although this is already implied by a result of kudla-millson, we give a simpler proof that avoids the complications in their paper.