Hi Dianne,
DS sometimes has green poo. I asked my MCHN and she said that not to worry about it if everything else is normal (i.e. he is happy, active, etc). She did ask if I fed him too much (in relation to to much foremilk which Trish has pointed earlier) or if I have had some green veggies or broccoli beforehand
One other thing that I noticed, green poo also appear after his immunization.
HTH and hope its nothing serious.