^^^ Really? It's actually proper in most places where they speak French (i.e., France, Quebec, etc.) to refer to men (including waiters) as Monsieur (Mister) and women as Madame (Madam). In days past, Mademoiselle (miss) was used to refer to young women (i.e., under 30) and only then if unmarried, but not in Quebec where--since its founding--everybody's a "Monsieur" or "Madame." [Note: these terms were actually titles reserved for those without any actual title (i.e. below the aristocracy whom alone would be referred to as "m’lord", "m’lady", which are formalities still used when addressing i.e. the High Court, for e.g.).] Despite this, people in the service industry---such as a waiter/waitress, etc.---would in all French places be referred to as 'mademoiselle' (miss) if female regardless of age or marital status. (Male waiters were called "garcon" (boy), but today are referred to as "monsieur" since calling a grown man a boy isn't proper by today's standards). 'Mademoiselle' is still acceptable when referring to a female server (so far as it's generic), but in no way makes it wrong to refer to her as Madame either: in other words, the only mistake was on her part and not yours, Jodum. I certainly hope that you did not leave her a tip! Could be the woman serving you, Jodum, is a stickler for the old rules and formalities (I still hope you did not leave her a tip), though most French women (as in, women not teenagers/girls) do not like to be called 'mademoiselle' today regardless of their age or marital status (i.e., draws undue attention to same), and especially not a professional woman in any case.