Hm, he does look a bit overly fat to me, toward the tail is starting to look like some butt suck is going on.
And if I'm judging size correctly, he looks thicker around than my 2yr old. But if he hasn't pooped recently, that might be what's causing the butt suck look. Otherwise, you caught him at a good point b/c some spine definition is still visible; once that's gone they're pushing toward obese.