My baby is 6 weeks old today and yesterday I put him on his tummy and he was kicking/shuffling his…

My baby is 6 weeks old today and yesterday I put him on his tummy and he was kicking/shuffling his legs and then he rolled over to his back!!! I put him on his tummy again a few minutes ago to see what would happen and sure enough after about a minute or so he rolled over to his back again! I thought this usually doesn't happen until around 4-5 months?! The day he was born I had him on my chest and he would lift his head up for a couple seconds here and there so maybe he's an early bloomer?