As I work in a secular office and not the church this is not an instance where two or more saints confront a fellow believer with a sin... and I think it's annoying, but not necessarily a sin... (unless her motive is to annoy) - but I think it's more like Ddavid from NC says, "keeping conversation cute and not confrontational" to build "walls that keep them safe". She is a self proclaimed Christian who attends a church on a regular basis. She has one grandchild who is 12 or 13... a little old to talk baby talk to. She has a devoted husband and her 84 year old mother lives with them and cooks for them. From her own statements her mother is demanding and bitter. Apparently her father who is now passed away had an affair on her mother and although he never left her, she never let him forget it to his dying day.
As Artsylady said, this is "an opportunity to work on my own tolerance and patience". The Good Lord can use this trial to make be better... but honestly... well, sometimes I just want to slap her! Rom 7:15 "For what I want to do I do not do,... "