I would file.
I am always cautious of customers who maintain small accounts with us and who obviously maintain their main accounts elsewhere.
I consider the small accounts with us just a set-up waiting to happen. Like what happened with yours and the $50,000. cash deposit.
Lots of people maintain cash at home, but unless the main account is with you and you can see the cash going out, I would consider the activity suspicious and file.
In the northeast a lot of investors set up small dollar savings accounts at mutual savings banks, in the hopes they will go public and get in on the IPO. Just a thought.