The question is related to this answer to a question asked on the Academia Stack Exchange, where the OP wishes to know the best way to address his PhD adviser in written communication. According to the answer:
As there exists a formal and informal way to say "you" in French, if your advisor uses "tu" (informal you in french), you could also say him/her "tu" because otherwise, it can be considered as you would like to put a distance.
Is this generally true? It is perfectly appropriate, for instance, for my manager to address me with "tu", but would it be considered "putting a distance" if I address him with "vous", taking into consideration the fact that he is much older than me with a decade's more experience?