Mine's fallen out a couple times too (had the same reaction at first: WTF is this?) Wish there were a better way to secure it than the 2 plastic clips that hold it in. :cry:
Check the manual? Ha! That's the worst book I have ever received. I could barely find the oil and tire pressure recommendations. Maybe I'm too used to McDonnell Douglas manuals, but I'm really disappointed in the lack of information in the Triumph book.