Car Auction

I sold my car to a buyer, i drove both of us to the dmv. in front of the clerk we signed the title, signed the form of "bill of sale" ( i did not have a bill of sale paper from her- since we work at the same place ) that the dmv had. turned in my plates. walked the buyer so that she can obtain her title to the car, which she only got a temp. - went to my insurance co. to cancel the insurance on that car -- this was back in june. today ( oct. 13th, 2007) i get a notice of lien of that car deman ding that i pay over $1,000.00 dollars from a towing co. with accuring rate of $20.35 per day until the day of the auction wich will be in november. am i responsible for that car?? help!! what can i do??

Nevada dmv . . selling a vehiclehttp://www.dmvnv.com/nvreg.htm#selling