Milo vomited up a lot of mucous for the first 24 hours or so, so I guess thats what it was.
The first time there was a fair bit there, so I called the midwife in, and she freaked me out by running out to get someone else to have a look. She looked at me with that "Its your first baby isn't it?" look, and said "yes dear, its just amniotic fluid" or something like that.