since Easter was in March this year, this isn't unexpected since a lot of revenue was pulled forward to March. The sequester offset part of the gains for the network airlines which rely on corporate and government traffic.
The unique factor for Dl was the devaluation of the yen which is hurting outbound Japan travel by depressing yields. While other airlines have Japan exposure, DL's is the largest among US airlines. DL did say it has a several hundred million dollar hedgebook for the Yen so they will be able to offset some exposure but the hedges are a small part of DL's overall Japanese operation.
It is precisely because DL sees the devaluation of the yen relative to the dollar as a long-term issue that they continue to develop Japan overflight routes including to China. Most carriers will suffer from a devalued yen but the solution will be different for each carrier.
DL continues to see stronger revenue performance later this year and quarter which validates the Easter shift.
Also, revenues will likely improve as the 717s start coming in and DL will very likely get a revenue premium in markets where it will have a mix of mainline service where other carriers are still using all RJs, many of them 50 seaters without first class.
As of this moment, DAL stock is the best performing US airline stock, DAL's market cap is pushing $15B, and the stock is pushing record high levels.