I think you did the right thing.
I still think that just because he never had possession of the cash that it could be construed as a cash transaction. Here's an example.
I saw a report where an examiner found a violation on a monetary instrument sale when the customer used a credit card advance to purchase the instrument. The examiner viewed it as two seperate transactions. One in which there was a cash advance for $3,500 and then that cash was used to purchase the instrument. I don't necessarily agree with that one because that cash is easily trackable but that was the examiners interpretation nonetheless and the bank had a violation cited.
I've also seen more examples of violations from lack of documentation and reporting than overdocumentating. In my opinion, it looks much worse to be documented for the latter.