does he have a dummy hun? if so will he get back to sleep with that?
It does sound like it's just out of habit and his body clock has got a bit messed up, I think if he keeps waking up you should try and calm him and shush him back to sleep and if that doesn't work maybe a little cuddle and then try again and if not then tbh I would leave the room but just wait outside and see if he goes back off after a couple of minutes.