Senator Amy Klobuchar finally lost her patience in Thursday night’s Democratic debate. “When we were in the last debate, mayor, you basically mocked the 100 years of experience on the stage,” the Minnesotan said to South Bend, Ind. Mayor Pete Buttigieg. “So while you can dismiss committee hearings, I think this experience works. And I have not denigrated your experience as a local official, I have been one, I just think you should respect our experience when you look at how you evaluate someone who can get things done.”

Senator Elizabeth Warren also took a turn at Mayor Pete. “Billionaires in wine caves should not pick the next president of the United States,” the Massachusetts Democrat said of Buttigieg’s much-discussed fundraiser with wealthy donors. “We need to defeat Donald Trump,” he shot back. “We shouldn’t try to do it with one hand tied behind our back.”

The spat with Klobuchar makes a great deal of sense: both candidates are vying to appeal to centrist Democrats; both are to some extent waiting in the wings for former Vice President Joe Biden to stumble; both need a strong performance in Iowa. The heated exchanges with Warren are also not totally unexpected—he has been a persistent critic of her “Medicare for All” proposal as he warns Democrats against tacking too far to the left.

But it was hard to avoid thinking some of this was a little personal. Concerns have been raised about Warren’s likability, just like Hillary Clinton before her. (“You’re likable enough, Hillary,” Barack Obama famously—and back-handedly—reassured her.) Mitt Romney clearly got on many of his 2008 Republican rivals’ nerves, though it was his frontrunner status that bothered them four years later. Buttigieg isn’t just unpopular with his rival, but also with internet progressives. The Bulwark’s Tim Miller notes that Buttigieg “has sparked blinding, irrational hatred from the online left” despite “mounting a historic candidacy as the first credible gay presidential candidate in American history.”

The Atlantic‘s Derek Thompson theorized: “Young educated liberals look at Buttigieg and see a nauseating caricature, not of the person they are, or even the person they wanted to be, but of the person they’ve felt pressured to emulate but never quite became—an outcome they regard with tortured ambivalence. Buttigieg is the guy they hated in college, not only because he was obnoxiously successful, but also because his success sat uncomfortably, hauntingly close to the version of success they once felt prompted to achieve.”

There’s also the fact that Senator Kamala Harris, D-Calif., moved left and then to the center in an attempt to gain a clear path to the nomination and instead was branded a phony. That’s why she has already dropped out. Buttigieg has done much the same thing and has so far gotten away with it. Maybe his moment with Klobuchar is a sign that is changing?