Why does the Torah say "uv'Roshei Chodsheichem" (i.e. yours), which it does not do for other Yamim-Tovim?
Seforno: It does so based on Yisrael's self-introduced custom to treat Rosh Chodesh as a sort of mini-Yom-Tov. 1
Seforno: Perhaps because Yisrael's destiny, which is dependent upon Hashem, is similar to that of the moon, which is dependent upon the sun for its light.