The coach of the University of California’s women’s basketball team was “appalled” after an employee of Southwest Airlines allegedly asked her to prove she was the mother of her biracial son before boarding her flight.

Lindsay Gottlieb, who is white, told KPIX she was questioned by the employee before flying out of the Denver International Airport.

Gottlieb also shared her story to Twitter.

“I’m appalled that after approx 50 times flying with my 1-year-old son[,] ticket counter personnel told me that I had to ‘prove’ that he was my son despite having his passport,” Gottlieb, wrote on Twitter, according to KPIX. “She said we have a different last name. My guess is because he has a different skin color.”

Gottlieb said she was not only asked for a birth certificate as a matter of “federal law,” but was also asked to pull up her Facebook page as a way to prove she was the mother of her 1-year-old son Jordan Peter Martin.

Gottlieb and her fiancé, Patrick Martin, welcomed Jordan last May.

Although Gottlieb and her son don’t have the same last name, she is certain the Southwest agent had racial motivations.

“The mother next to me said she’s never been asked for proof” when traveling with a child who had a different last name, Gottlieb tweeted. “Not shockingly, not mixed-race family.”

Southwest has since reached out to Gottlieb to “address her concerns,” according to a statement shared with Fox News.

“We’re looking into this specific interaction, and we have engaged with the Customer directly to address her concerns,” the airline wrote. “Our Employees are well regarded for their Hospitality and we always strive for the best experience for anyone who entrusts us with their travel.”

Gottlieb also said that while she was dissatisfied with her experience, she is aware that it happens to Black women who do not have a platform to speak out. 

“I do feel like as a white female, with a position of privilege, and a platform where someone is going to listen, it is my responsibility to say, 'Hey, this happened, this isn’t OK,” she told KPIX. “And maybe somewhere down the line that helps my son, who is biracial and will be for his entire life.”