If you were issued a judgement by a court of law, signed by a judge and you fail to pay the judgement or make arrangement to pay the judgement, whoever you are required to pay the judgement to is, able to file a lien against the property.
You do not have to be notified that this lien has been filed against your house. Any lien is public records and is available to be viewed by anyone. You are able to see if there has been a lien filed against your property.
You know there has been a judgement issued against you, signed by a judge. Apparently you made no effort to make arrangement to pay the judgement or pay the judgement.
The person that was awarded the judgement is entitled to protect himself. If this person failed to file a lien against your house , you could sell or refinance you house and this person still would not be paid.
I hope this has been of some benefit to you, good luck.