A contractor is required by law to send the owner a copy of the mechanic’s lien they are filing at the time of filing the lien, so in most cases you will know. Just to be safe, I would also check the on-line records of the County Recorder’s Office in the county where the property is located. Most counties have this information available on-line. You can check the index under both your name and the contractor’s name. Depending on the county, their records may be a few weeks behind so you may want to keep checking as time goes on. I’m happy to answer any questions you have about this.