I'm not a lawyer, and I don't know of any case law on this issue or anything. In my opinion, it is a sticky situation.
I have a little background in law, and here is what my take is on it. If you ever used the card with your name on it, you could potentially be held liable for some of the charges. Why? The fine print on every credit card receipt that states you agree to the charges and agree to pay. By signing that receipt, you are agreeing to this. So, even though you did not sign the contract on the account...stating agreement to the credit card terms, interest rates, payment, etc....you agreed on each receipt to pay the charges.
Now, that is if you look for a loophole. In my opinion, I do not think they can go after you, just for having a card in your name. You did not agree to the terms of the credit card. Now, if you charged up the card, the person who did sign the agreement could potentially use the argument I made above in a small claims court to get you to pay for charges you made. However, I don't see that holding up in court for the other person against the credit card company or a collector. As I was told with regards to my ex-husband....he had a card with his name for my accounts, but I was the one who applied for the card and signed the agreement...I only asked later that he be given a card to use the account (reluctantly, mind you). When we divorced, I would be held liable for that account, and they would never go after him....because It was my name on the credit card agreement. The credit card company did not care that my ex was the one who made the charges!
I would send a debt validation to LVNV ASAP...overnight mail, certified/return receipt. Now, they will not validate, as many here will attest to. However, it will show that you have tried to make them prove up that you are the person they should be going after. I would go to the pre-trial conference and immediately use the defense that it is not your account...that you demand they present a contract signed by you. Sounds to me like they are grasping at straws, because they couldn't get the contract holder to pay.