From the article, which includes zero claims of any acts of racism against him worse than the following:
I see that a security guard follows me as I go through the department store, and I’m reminded that, oh, I’m also a black scientist — because that’s how society sees me... Now, all these things I’m describing to you were common 10 years ago or earlier, and decidedly less common today. So while many will complain about the status of race relations, I have direct, empirical evidence that it is vastly better today than it was 10 years ago — and my worst stories don’t compare to those which my parents could tell when they were growing up.
Also, 10 years ago, there would be taxis that wouldn’t pick me up in the street. But that’s basically not true anymore. Back then, it was one in five taxis that would pass me by – empty taxis that were ready for a fare. Nowadays that number might be one in 50. It still happens, but it’s rare. It’s rare enough to chalk it up as “maybe they just missed me.”