Which is that to repeat such a comment is possibly quite tactless, even if there are no particular reasons for it to hurt - ie, none of us would want to hear that a 'slight acquaintance' thought us so altered, presumably for the worse as Mary prefaces it with the remark about gallantry. So Mary is not bothered about this ordinary level of pain she might be inflicting. She is not, however, aware of any deeper reason for the remark hurting.