There are some thicker superglues (CA glue) out there that are perfect for these type repairs. They are clear, take very little to hold, and set in about 10 seconds, so you can hold it in place easily. I use Gorilla SuperGlue (not regular Gorilla glue - that's a good glue but not for these tiny repairs). I'd wait until the rest of the piece is cut, then go back to make the repair (don;t repair then try to keep cutting unless you let it sit an hour or so).
Check the pattern to see if a floater snuck in there. Steve is a terrific pattern maker but doesn't always cut a pattern before publishing it. If you find that the part that fell out was a floater, post a note to Steve so he can correct it.