A conspicuous case of senior-to-junior narration is a teacher reporting from a pupil. The pupil may have heard a report from another master or acquired a reliable reading of a text and then conveyed that specific item to his own teacher.
A chain in which a recognized teacher cites a pupil should not be dismissed merely because people usually imagine knowledge moving in the opposite direction.
The particular report still requires examination: did the teacher in fact hear it from that pupil? An established teaching relationship by itself does not prove every alleged transmission between its participants.