Shoot! I bought a used Legacy a few years ago and didn't get one (didn't know I was supposed at the time!). I was hoping it might be mine!
If it's not in the registry, it's going to be tough.
As Jamie suggests, it's possible it went with another guitar the e-bay seller had and it was mistakenly put in the wrong case, so that would be the best place to start.
The only other thing you could try would be to contact G&L, they might know who the original instrument was registered to...though I'm guessing it's been sold since and they likely have no idea who owns it now.