I had this too on a couple of occasions but it disappeared when I altered her position so I put it down to circulation and me noticing it because her skin is so translucent.
It's normal don't worry. Its because the body prioritises getting blood to the brain and lungs as the main organs the feet and hands come second. It will level out soon x
Is it only happening when he’s in your arms? Are they cold? It’s normal for babies to have hands and feet like that. As long as their body temperature is ok I wouldn’t be worried