Rebbetsen?

Question:
Someone told me that there is a custom not to refer to the wife of a rabbi as a "rebbetsen" unless that rabbi is functioning as a the rabbi of a synagogue or as the head of a yeshiva. Is that correct? What is the source of this custom?

Answer:
I have never heard of such a custom. Nor have the colleagues that I have consulted. I have been unable to locate mention of such a custom in the literature that I have consulted. If any readers of this blog have anything to contribute on this matter, it would be appreciated.