I believe the s-boxes were provided by the NSA without much comment about them.
You're probably thinking of DES rather than AES with regards NSA provided s-boxes. IIRC said s-boxes in DES were changed by the NSA with no real explanation. Some years later when differential cryptanalysis was discovered in the non-secret world it turned out that the change actually hardened DES against such an attack - so in this case the NSA created a stronger algorithm. See wikipedia.