My second girl was the same.
Our doctor told us it was hormones too, and that baby girls sometimes even produce milk!
I never saw any milk, but I stopped brestfeeding her at about 3 months, and they did'nt go away.
She's one now and still has her little baby boobies! When she was crawling we used to laugh at her cleavage!!
She's just a little fatty, and that must be one of the places she deposits her fat.
She also still has little fat arms, an "extra" bum, and dimples and creases everywhere.
She's the complete opposite of our first daughter, who actually ate way more!!