Yes, the story goes that the NSA assisted IBM in its development by tuning the specific values in the S-boxes to be resistant to differential cryptanalysis, which had not yet been publicly discovered.
They also reduced the key length from 64 to 56 bits. I found this suspicious and didn't accept the explanation that those 8 bits were needed for "parity". Yet, respected cryptographers say this actually brings the key size more in line with the effective strength. So those additional 8 bits in the key were not contributing to the security and it improves the "truth in labeling".
Why would they build weaknesses into standard blocks, the biggest consumer of which is the US government itself?
When the NSA had at times insisted on an upper limit for a protocol's security (e.g., export crypto), they usually would require a simple upper limit on the number of secret bits in the key. When they've submitted fixes they tend to be elegant and minimal (e.g. SHA-0 to SHA-1).
