Can a baby start social smiling and vocalising at one month?

Our LO is nearly five weeks old now and in the last few days we've noticed an increased frequency in what appear to be smiles and vocalisations.

The smiles seem to come particularly when someone's face is close to his, like if he's being changed or we're fussing over him in his Moses basket, and in terms of the vocalisations there's definite sounds that seem to be repeated, particularly a kind of barking "WAH" that he does when he's very awake and engaged and seems to be asking for attention/play.

I'm conscious this is still quite early for those kinda of things but then he was born at 42+3 so I'm wondering if that could factor in?