Eh normal je tu! Mixed feeding memang boleh buat warna najis jadi campur-campur, green at greenish-yellow tu common sekali especially kalau ada formula involved. Sebab digestion dia lain sikit compared to pure breastfed babies. Since your baby was premature and spent time in the ward, mixing both feeding untuk boost weight gain is smart move, doktor pun recommend kan. Just monitor je kalau najis dia ada mucus banyak or very watery terus-menerus, then check with your pediatrician, but the color alone sounds totally fine to me lah!