So we generally use the target brand formula similar to the enfamil gentlease but recently bought the Walmart brand since we were there and it was cheaper. I have noticed when my son gets to the very end of his bottle there are always little black specks in the last few drops in the bottle. I don't notice anything in the formula container when I'm making the bottles or when he's drinking it just at the very end. I've done some googling and saw something about it being burnt formula from when it's made? Has anyone had a similar experience with this and know if that could be it? I always take the bottle away so he doesn't drink it and I haven't noticed him acting any different but just wanted to ask around.