Google Agenda is not that clever apparently, it's showing me the event at New York time despite me being in France :P
So 1 hour after deadline = 11pm UTC, I'm sending a tweet about it!
@Wan, you probabaly opened it up in a non-Incogneto chrome tab. I had that same issue. Worked correctly in FireFox (both normal and private) and Incogneto in Chrome… but not a non-Incogneto tab in chrome.