Green poo😕

So I'm exclusively breastfeeding my LO and he's really helped bring in my supply from nursing all day n night (except for a bottle of pumped milk at night for my husband to give him) and I'm a little worried he might have gotten too much foremilk at some point recently cause when I just changed his diaper, it was mostly yellow but for he first time, had some green poo in it. He's a month old and this has been the first time. I always let him eat off one breast per feeding so he gets the hind milk but I'm thinking maybe the one breast was too full for him?? I hope I'm not overproducing now. I only pump once at night when he gets the bottle and get 3-4oz at best w/the pump. Is it possible to get green poo w/out there being a foremilk issue?? I'll prolly just pump a little before I feed him now😕