To the OP,
The only thing additional I would suggest (for the future, as you've already shipped) is that you verify the validity of the FFL before shipping. You want to know that (A) they ARE legitimately an FFL, and just as importantly... (B) that their license is CURRENT.
Go to Google and search "ATF FFL check" and you will find an ATF site which allows you to enter only the first 5 and last 5 digits of their license number (some are squirrelly about giving out their full number). The site then verifies their GOOD TIL date on their current license, the business name, and address . . . and if the FFL balks at giving you their first and last 5 digits, tell the buyer they need to find a different FFL to receive.
It's a minor quibble, but it's FIRST THREE and LAST FIVE.
