Maybe. The first question that comes to mind is, "Why?"
WHY would someone just give you a prepaid card and allow you to pay bills with it? Is this person rich? Is this person someone who owes you money? If so, how and why? Most of us would ask ourselves, WHY is someone just giving me a prepaid card to pay my bills with? This just doesn't happen in the real world ... but, it does happen in the criminal world where people make all sorts of arrangements. If you have a criminal history (dope, theft, fraud, etc.) then that history will definitely play against you.
While you are under no legal obligation to say anything to the police, if they can show through the totality of the circumstances that you knew or reasonably should have known that the card was stolen or somehow obtained through larceny, then you can be charged. You might get lucky and they might simply ask you to testify against the person that gave it to you.
So, the answer to your question is, "Maybe," or even, "Yes, you CAN be charged." Whether you can be convicted would depend on a whole lot more information ... and you'd better hope that the other guy doesn't dime you off in an effort to get a better deal himself!
