In a brand they've always worn, that is. I thought he outgrew 0-3 a while back so I accidentally grabbed an old sleeper and was surprised to find that it was huge on him. So then I dug up a 0-3 onesie and realized that it was also loose, and the 0-3 pants that I set aside weeks ago because they were too tight in the waist now fit fine with some room. What the heck? Does this happen?