Looks like astral feedback. Your half- projected realtime body was more than likely hitting up your instinctive fear 'intruder alert' response, and more than likely turned into a warning scream from your subconscious. That can happen to anyone, new baby or not. It does happen at least once, and not always the first time, so when you think you've 'seen it & done that', it happens and baffles you, because it's not a 'rational' fear- it's like a tickle in the fear part of the amygdala which can be hard to deal with.

BTW, the care of a new baby is an intensely spiritual experience, especially when they start sleeping through the night..