Yup, DD did this too, especially when she was sick. Midwife said it was all fine, not to worry.

As an aside, the larynx in newborn babies stands up high, so not only can air get into the lungs more easily (babies can actually couple the back of the nasal cavity directly to the larynx so they can drink and breathe at the same time!), even when the larynx isn't coupled to the sinus, milk can flow down either side, so they don't choke whether the milk is coming up or going down and they can use the nostrils as an overflow valve if the milk is flowing fast. Pretty amazing! The larynx descends as we age, and some scientists believe that because a descended larynx allows a far greater vocal range, it is what allows us to talk so well and was part of our evolutionary journey to being the dominant species.