So many "aunts"

Samantha
Anyone else experiencing women that they know calling themselves your babies "aunt" even though you aren't related at all?
For instance, a woman I work with keeps saying things like "Aunt (her name) can't wait till that baby is here, I'm going to spoil him so much." Or even if I say something like "Little one was being so stubborn this morning." She will say something like "Oh he gets that from his Aunt (her name)."
These are the most extreme examples from one person but there have been several other people who refer to themselves as my baby's aunt when we aren't related or even that close at all. 
Of course I am so appreciative of how loved my baby already is by so many people, but I don't really know how I feel about the "aunt" thing because I know I won't refer to those people as Aunt So-and-So to my child because I'm personally not comfortable with it and I'm not really sure if that would hurt that person's feelings. Is this a silly thing to worry about?