Thanks for reaching out about this. The referral discount is valid on the first Glowforge purchase for each person. In this case, it would have applied to the first Glowforge, but not any additional Glowforge purchases. I apologize for any confusion.
You can learn more about the program at http://glowforge.com/referral-terms.
I hope this helps - anything else is unclear, you can reach us at support@glowforge.com