It still should still be there unless you completed 20 levels. The event timer was over 2 weeks so there is still a lot of time left. Did you change anything to do with your clock settings? Is there a timer showing under your lives in the top left corner?
I still have the Valentine's day Event on my game....Im on level 18 now!! Its really fun! I love the new background and levels...It's easy to pass the levels. Maybe you need to update your app after the last update..