Hi and welcome to the boards!
The average A time at his age is between 3 and 4h, so for sure his first A time is too short for his age. The second one is a bit trickier to find out if he is UT or OT because he is doing pretty much the right A time.
What I would do IIWY to get the A times right is to start and increase the first A time by 10-15min every 3-4 days until you are at around 3h A time and shorten the second A time to 3h and stick with that for 4 days. If after 4 days you are still getting short naps in the afternoon I would start and use the same system to increase A time - 10-15min every 3-4 days till on the 4th day you get a better nap.
If all that won't help then it's probably a sign he is starting the 2-1 transition. Don't worry, it's going to be a while before he drop the nap entirely, but many babies start to cap one of their naps or we need to do it for them.
HTH
