Mechanic's Lien delivered without notice of intent

[Jordan Sachs]

My friend's husband owns a property in Bethlehem. He's used the same management company for years. He owes them some money for work that they did and they filed a mechanic's lien on his property 3 weeks after he received the bill which was also one business day before he was scheduled to sell/close on the property. (he was able to close because the title search had already been done before the lien was registered) 

According to him he has never not paid them for previous work and he never said he wasn't going to pay them but as soon as they found out he was selling they filed. They gave him no notice of intent to lien and clearly were trying to mess up his sale. Now the property has been sold and it has a lien on it. He still intends to pay the mgmt company. Is this lien legal even though they gave him no notice? They couldn't have given him a 30 day notice if they wanted to because it hadn't even been that long since he received the invoice. Does he need an attorney or should he just pay the invoice in full? Thoughts? TIA!