Entire precursor group of galaxies should be all made of antimatter as well. A single galaxy can't have antimatter stars because of the way the whole galaxy as well as individual stars form through the accretion of gas. If any portion of that were antimatter, it would meet and annihilate with normal matter very early in history.

However, seeing as how just after the Big Bang the universe was rather homogeneous, the whole matter-antimatter imbalance was resolved by annihilation very early in the universe, and thus it is nearly impossible for any significant lump of antimatter to be left after this early process.