Can the supplier file a mechanic's lien?

I have hired a general contractor to put an addition on my house. He then hired a concrete subcontractor who turned out to be a fraud. My GC paid the sub just over $13,000 in advance (he's going after him separately). The concrete supplier was given a bad check by the sub for around $5,800 and the check obviously bounced. I work in construction for an aggregate company that is a supplier to the concrete company that was given the bad check. They know I work for the aggregate company and called me at work to threaten filing a lien on my home property. Instead of letting my GC pay the bill and be done with it, they trusted sub when he said he would make payments (though he was in jail for numerous days). As of yesterday, they have sent out their notice to file lien on my property which is going to alert the Farm Service Agency who holds the loan on our house, acreage, cattle, and machinery. I have a couple questions: Can the concrete supplier actually file a lien on my property even though my GC has given them proof that the sub was paid for more than the amount of the material? It sounds like they will still be filing suit for the bad check even if my GC pays them in the next 10 days, can they actually do this? Lastly, are they allowed to track me down at work and call back in February to threaten a lien when the only reason they knew my place of employment is because of my business dealings with them?