For several days now, Milton--4 or 5 months old now--is puffing up for about 5 min when I wake him up for the day. I have him on a relatively regular sleeping/lighting schedule. I don't think he's sick, just something strange I noticed. He's done this every day since I got him, so It doesn't seem unusual. I think it's because he's not a morning person. haha just like me!