not pregnancy related but really bothering me

Br
So I work for a bakery. Today my manager had an interview for a part time decorator. My coworker asked her how it went, and if she thought she would hire her. My manager made a face like 😬 and then said, "It went well, but I don't know, she's mentally challenged." 
I have reaaaaal issues with this. My niece has Down syndrome and it makes me think of her having trouble getting a job because of someone like this. 
Should I go and report it? Other people heard but they just pretty much ignored it and called her immature. But it's really bothering me the more I think about it. Like there was no reason to even mention her disability. She was obviously qualified if she made it to interview process with a manager.