While complaining is ubiquitous in everyday interactions, it can seem out of place when a teacher complains within a setting devoted to reflective practice and professional development. In this article, we show examples of a novice teacher's complaints to her mentor within post-observation meetings, making the case that these complaints raise issues relevant to reflective practice, including teaching beliefs and dealing with critical feedback. We show how the mentor sidesteps the issues raised by the complaints but suggest that mentors could treat complaints as a novice form of reflective practice. Ultimately, we offer practical suggestions for anyone engaged in providing post-observation feedback.