Here's the relevant Q & A from the OFAC web site:
Does my bank need to check the OFAC list when selling cashier's checks and money orders? In the case of cashier's checks, do I need to check both the purchaser and the payee? As a mortgage lender, do I need to check both the purchaser and the seller's name against the SDN list?
Every transaction that a U.S. financial institution engages in is subject to OFAC regulations. If a bank knows or has reason to know that a target is party to a transaction, the bank's processing of the transaction would be unlawful.
This is my career favorite piece of "regulatory speak." Please note that it does not actually answer the question, it just appears to say, "Yes." It suggests that making a check payable to an SDN, even at the direction of a third party with the third party's funds, is the equivalent of dealing with the SDN in violation of the sanctions. That's an interesting, unsupported leap, but it's one they are prepared to make. Many examiners believe this is a directive, not an observation.
To my knoweldge, these folks have never said any proposed transaction was not subject to OFAC. I'm confident they would say the the presence of an escrow relationship did not work as a "blind" in your circumstance.
However, I'm equally confident they would say that a commercial vendor picking up the trash at an SDN's house or Circuit City's selling him a 9 volt battery was in violation of the sanctions.
The answer is always, "Yes."