With a hotfix today, Blizzard has added a new hidden quest tracker for the first time in the day you defeat Daetan Swiftplume. This likely means the event works similarly to other Holidays, having a higher chance to give its finest rewards, like Noble Flying Carpet, in your first attempt of the day.
The hotfix happened sometime in the afternoon (Pacific Time), and it added the new hidden quest tracker , which gets flagged as completed when you turn in the daily Feathered Fiend.