Sadly, we rush to put the paci back in. Our LO is the same way and if it falls out for too long he gets really fussy and the longer it's out the longer it takes to get him back to sleep. Basically we are a slave to it! Hopefully only from a little while longer, but for now....that's us.
This is us as well. If he gets to a really deep sleep, then when the paci falls out he's ok. However, LO is really fidgety even when he sleeps and sometimes he wakes himself up by jerking awake. They'll eventually grow out of it, I just hope it's sooner than later!!