1 month growth spurt??

Judith

My baby is 5 weeks and 2 days. Yesterday he’s slept basically all day and slept through the night and is STILL sleeping right now and it’s 9 am. I fed him 3 hours ago when he naturally woke up. He’s gaining weight well but he’s only had 2.5 oz from that one bottle. I hear you don’t wake a sleeping baby but wow he’s sleeping SO much. Is this something I should be concerned about? Is this a growth spurt thing?? Idk.