What surprised me most about the story is that despite a very unusual pattern of transactions for a business banking account at a local branch, the OP only received occasional calls from the local branch banker. I would have expected at least one call from the bank's compliance department inquiring about the source of the funds, and requesting more information about the nature of the OP's business. Bank's are legally required to know their customers and to report potentially illegal activity. This account clearly did not go unnoticed.
I have received such a call from Chase only once in my 35 adult years, and it was triggered by a deposit much smaller than 35M.
They wouldn't have looked at it as a one-off $35M deposit though, but as one of many increasingly large deposits into a tech company that could all be traced back to a VC firm - all of which could be verified by information the bank has available without needing to query the customer, not least a series of effervescent PR pieces by said VC funds about their new investment
I have received such a call from Chase only once in my 35 adult years, and it was triggered by a deposit much smaller than 35M.