Hi, I'd leave him to it if he's not upset. With any new skill they practise at BT and naps so just try and practise as much as you can in A time. Generally these things pass after a couple of weeks. I used to find my LO upside down, sideways on, feet up the bars you name it ha ha!! Sometimes I used to sneak in and straighten him up but not often for fear of waking him!
I'd loose the insert if he's now mobile.