Every child has a different endurance, and, can be feeling unsafe in ways we can't understand. For them, the world is still new and they can't seem to adapt everything with a lot of ease. Some babies can start to get comfortable a little sooner than others. We shouldn't have to force them to feel that. But I would suggest, you keep in check if it gets any more unusual than just a little prolonged ease. It can also indicate overly shyness. so, be polite, and stay with him as much as possible. You can try sleeping with him rather than making him sleep alone, this might ease him out a little. Thanks and good luck.