6 week old has diarrhea...What do you think?

My 6 week old has had very watery stools for almost 3 weeks. I showed the pediatrician this picture and she said it’s more watery than she would like, but because he’s gaining weight and in the 95+%, she’s not too concerned. His stool used to be yellow, mushy and seedy but now it’s very loose.

He’s formula fed. I know the green color is because of the iron in the formula, but the consistency worries me.

I know she’s the doctor, but what do you think?