Here is a video of the aforementioned coo. It usually occurs after a sneeze but has been none to happen before. While the coo is fairly common it's a bit like Bigfoot in that it's hard to catch on video.
Update: I should also mention that today, the day after I posted this, Miloh is a month old. So happy Month-day Miloh! Also I will be soon posting a graphic on his first month combined.