Hi Audrey,
As long as he is not crying, I would just do your night time wind-down ritual, lay him in the crib, give him good night kisses, and walk out. He might play for a while, but I would stay out of the room and let him fall asleep on his own. If he does cry, (and it is more than a mantra cry) then you can return and do shush/pat or PD, etc.
It sounds like he just might be a tummy sleeper, which is just fine at his age.
**Oh, also, do you get sleepy signs from him before bedtime?