Hi hon- yeah, that A time looks too small for his age. I would try adding 10/15 minutes every day until you are up higher. Usually at this age you ae closer to 3 hours A time. If you jumped to that right away that wouldn't work- but a slow increase until you get a longer nap might help. The 40 min nap is an indication that he is undertired.
At this age the sleep cues can look VERY much like boredom, and are really unreliable. If you feel he is looking tired try a change of scenery, or a different activity as this might stretch him further.
How many naps is he currently on?