Are offhand comments about this employee’s dress cause for concern?

Q: “I work with a manager who just gave a performance review to one of his staff (an administrative assistant) in which he gave her high praise on her work performance and then shared that ‘someone’ in the organization felt that she didn’t dress professionally enough. This admin does not interact with the public; she mainly sits in her office, generates reports and maintains websites. Her attire is neat and clean but not fashion-forward. She is also a single mother getting no child support. The comment about her appearance shocked her and now she is feeling embarrassed and alienated from the rest of the group. She mentioned talking with our Employee Concerns office. Where do we go from here?” – Anonymous, Washington