Loud grunting and pushing noises while sleeping

My baby boy is 16 days old and while sleeping (more in the early morning after a few night feedings) is constantly grunting and seems to be making pushing noise. His legs are kicking in and out but he seems to stay asleep. At first I thought maybe he hated being swaddled but after some looking online it said it could be gas and reflux. Has anyone experienced this and how I can resolve it. Should I call his dr? Hoping we can get fixed and each have a better night sleep!