You know what I am finding is that sometimes OT accumulates and F just needs to go down a bit earlier one morning. That was this morning, after a few days with short crappy naps and nights that haven't been great, I put him down earlier this morning and now he is doing on 1hr 20mins still napping.
It's tricky, because on one hand I try to hold him to his normal A times and keep him on track. But sometimes he just needs to catch up, so I have to do a day with shorter A's. This situation is normal I think, the key is to know when to push and when to back off!
Anyways, sounds liek 1hr 20mins is all I'm going to get as I hear him up. Still, better than 30mins!