I have a question about a lien put on me?

I was in a hit and run car wreck back about 5 months ago. Another car ran the red light and smashed into the car. We had uninsured motorist on our auto insurance and they are paying for my medical treatments x-rays and hospital visit. I also had medical insurance which I used the time of the wreck at the hospital. I Just found out there is a lien on me for a hospital bill of $1100 for the night I went to the ER. I dont know why they have a lien on me when my attorney is handling everything and so is my insurance. I have never had a lien on me before. I was told by a friend who use to work for a lawyer, that the hospital automatically puts a lien on you after 90 days for auto accidents? How true is this? The hospital will get their money when everything settles but in the meantime, this lien is hanging over my head.