Is bank legally supposed to notify cosigner when debtor files bankruptcy?

I cosigned for Harley for stepson - he filed Chapter 13 then changed to Chapter 7 without informing me. Harley was repossed, now I am questioned by bank. when will I pay remaining $10,600? The bank never notified me that stepson was late on payments, or that the Harley was to be repossed?? Was the bank legally responsible to contact me??