I would have thought that the circumstances would justify it even in that period. I am no expert in the period and thus what I write is not science but a feeling. But I thought that her role as the Mistress of that house gave her formally both the precedence over and the duty to safeguard the comfort and sensibilities of all her guests.
Telling off any person is unpleasant and towards your mother more so. We can debate if this happened in an appropriate way and setting (I think so). However, in terms of norms and morals, my feeling is that she was justified under the norms and morals of the society. I may be wrong (in any scholars on the topic are among us...?)