I've read it's fairly common and it phased out for a while, but recently come back. Baby talking, acting like a baby, he even breaks out of character to ask how a baby does xyz and then resumes!
It's often around me to me. It drives us both potty (dh and I) but I see more of it and try to be patient.
I'm just trying to understand it a bit more. And how to respond. Some of it is when he wants cuddles but it's really wearing. And I don't get why we can't have a 'normal' cuddle!
If I am able to distract with a more interesting think it can break it but not if he's tired.
I'm aware that we are reaching that 6 mo disequilibrium thing 