I would definitely let my clinical instructor know. And if she starts looking in charts of patients not assigned to her, couldn't you just say out loud for everyone at the nurses station to hear, "Wait, that's not your patient, isn't that a Hippa violation? Looking in the chart of a patient that is not yours? The hospital could get big fines for that." or something along those lines? And perhaps mention how four nurses were fired at that Arizona Hospital where Giffords is a patient because they looked at her chart and she wasn't their patient.
(Every time there is an incident like that, our NM has a meeting about Hippa violation and do not look into any patient's electronic record/chart because they will know and then come to you and yes you will be fired if you cannot explain why you looked at their record.)
Well stay strong and just know that you will be a better nurse! :)