His first A seems short for his age - I guessing you're counting wake up as 7.30? The average A is 1 hr 15-20, so you might be getting an UT nap, and then developing OT as the day goes on perhaps? I would boost his A times gently and see if that helps him nap for longer, try adding 10 mins to his A time and see how he goes. Give him about three days to adjust to the new time.