It depends on how much sleep he's getting at night. Is he sleeping well at night? How long? Around 1 yr of age, he should be getting around 10-11hrs of sleep per night plus 1-2 naps a day with naps lasting about 1-2 hours each.
It's possible he may not be sleeping quite long enough for one of his naps, which accounts for his need to take a third short one. It does seem like a lot, but I don't think it's excessive, but you didn't say how long he's sleeping at night, so it's hard to tell. It's also possible he could be in a growth spurt, during which he'd likely sleep a little more.
If he's not getting enough sleep at night and making up for it during the day, it might be time to shorten his naps a little and up his bedtime slightly, allowing for more sleep time at night. The range I stated above is the average, but some kids need less and some need more. It really depends on the child. Every child is different.
If you shorten his naps and up his bedtime, and he's still not getting enough sleep at night, I'd talk to your son's pedi about it, just to be sure. Don't get too worried about it yet. It could just be his body is changing and his sleep patterns are trying to adjust accordingly.
Hope this helps!