Newborn restless when settled

Hi my LO is just over a week old, and everyday it's great to see him more and more explorative. However I've noticed that when hes settled he becomes really restless flinching his arms, gripping his clothing and murmuring etc - to me it looks like it's perhaps a sign he's uncomfortable with something but it's so hard to tell when there's so many possibilities (heat, itchy clothing, itchy belly button where cord has fallen off, wind etc) so I'm just wondering primarily if this seems normal behaviour for a newborn? He seems to get really frustrated with himself, and it breaks my heart 🙈