Work Flow mailer Purchase Requisition

hello We have come across an issue where a user has generated a purchase requisition . It has to go to for approval to his supervisor. Instead of going to supervisor it has gone to Supervisor's boss . Status still in Process. Why it has gone to Boss and how to resend to its approver / Supervisor. There is no change in setup of Approval Hierarchy, not to Workflow. Thanks Gobind Ahuja