Mentoring is not Monitoring
I agree, mentoring is all about the needs of the mentee and where they want to be, so the mentor can advice and guide.
Your activity sounds more like critical appraisal, and the feedback you received lacked constructiveness. This can undermine confidence and hence effect performance.
When receiving feedback
it is important to remember that this is someone's opinion, ask for evidence, then consider whether or not you accept it. Ask yourself what is your evidence to counteract their opinion. The important thing is to be honest with yourself.