It's really hard to see in your pictures, but if I had to guess, he's either clamping strangely, or was just born with weird fins. My girl has one of her bottom fins longer than the other, and a bent spine. Sometimes they just aren't born smoothly, etc.
If you can take more pictures of her fins, I could try and help more, but form what I see, I don't see the usual signs. Look up "fin rot betta" on google images, and you'll see that the fins look tattered usually when fin rot is the culprit, which I don't see in your little guy.