Haunted: Do you know if they collected a split specimen? (2 vials instead of 1) If a split specimen was collected, you can request the other vial be sent to another lab for testing. If they think it's byproducts of something like Ambien, and you have a script for Ambien, I would think you should be ok, even if it is old. And even if that really isn't what you too, since that's what they think you might have taken.
Sorry for all the stuff you're getting dragged through...what a pain!
LPNtoRN: Lortab taken a couple months ago won't show up in a drug test done in January, so you don't have to worry.