context: In September 1958, Bank of America launched a new product called BankAmericard in Fresno. After a troubled gestation during which its creator resigned, BankAmericard went on to become the first successful credit card; that is, a financial instrument that was usable across a large number of merchants and also allowed cardholders to revolve a balance (earlier financial products could do one or the other but not both). In 1976, BankAmericard was renamed and spun off into a separate company known today as Visa Inc.
question: What month did the BankAmericard creator resign?