ArenaNet is shipping the Lost Shore event item – the Ancient Karka Chest – to those that missed it, due to disconnects or “no-reward-occurences”, now. So if you participated in the event and did not get the reward chest, there is a good chance you will find it in an in-game mail during the next few hours.
Not all mails are sent at the same time, so don’t panic if you did not get your mail yet, while other people have already received it.