Price signaling. Since companies can't legally collude, Delta is announcing to its competition (through the media) that it would like to add a fuel surcharge. Other airlines will either match, or refuse to match to gain market share.

If other airlines announce the same, Delta knows they will be able to make it stick. If other airlines announce that they are not going to do it, Delta might reconsider. This has happened before. Last time, no one took the bait and Delta never added on a fuel surcharge. This time, due to high demand, the other airlines might match.