I don't know if I would use the word "upset" precisely. Rather I would use the word concerned. When the Watsons finally reach Birmingham, Alabama in Chapter 12 and are reunited with Grandma Sands, it is clear that Grandma Sands has a gentleman friend who she is very close with. Wiloma, as her mother's daughter, is rather taken back at this, especially because she has never heard of Mr. Robert before, and so it comes as rather a shock to her:
"I just don't understand what's going on here. How come I never knew him? Did Daddy know him?" Momma said that last part like she was dropping a bomb on Grandma Sands.
However, Grandma Sands shows that she lives up to her formidable reputation in the way that she responds to her daughter, saying her words in a way that made "everybody who heard it shut their mouths and listen real hard." Wiloma is forced to accept that, as Grandma Sands says, things have changed a lot since she left twenty years ago, and now Mr. Robert is "the dearest friend" of her mother.