Board Thread:Game Discussion/@comment-9182195-20130506171655/@comment-8564792-20130506212656

They transfer to regular silver and gold medals once the event ends. For the Dinobots event they specifically stated that until X date (I think it was about 48 hours) you still had a chance of drawing the event-specific cards (probably to find alt forms of cards you got during). They didn't mention that during the last one, though, so I'm not sure if they stuck to that.