Hi
Sorry your post hasn't had a reply as yet!
That first A time looks ok at 2.5hr and seems to produce a reasonable nap, its on the short end for a baby this age but that's not necessarily a bad thing. If he's having long happy wakings in the early hours of the morning or waking progressively earlier in the morning, then those are good indications that he needs more A time and he's doing what he has to to get it. Making his nap a touch later than it 'should' be by A times can help pull the morning WU later again.
Those 30min naps... I think he's probably OT, at least for the 2nd one. I wonder if there's a trigger for him to wake? White noise stopping or something? My though wrt that is that if he sleeps 30mins and you cannot resettle for the second nap of the day, his A time following that could be slightly less than normal at say 2:15 rather than pushing him to nearly 3hr off a short nap which will certainly yield another OT nap.
Another potential culprit is overstimulation or understimulation. Babies can get fussy and look tired when they're ready for a change of scenery/activity so its worth changing things up if he's fussy and you're trying to extend A times.