At last, Bill Clinton could not help himself.

He paced the stage during a speech on Tuesday in North Carolina, holding his microphone close. He raised his left index finger. And at once, the meandering address turned sharply, and without prompting, to his charitable foundation, a magnet for criticism in recent weeks.

“We live in a Snapchat-Twitter world,” Mr. Clinton lamented, tilting his head theatrically — a septuagenarian embracing his age, decades after reveling in saxophone cool.

“It’s so much easier,” he said, “just to discredit people and call them names.”

For Mr. Clinton and his extended circle, this election has at times felt like a campaign devised to discredit the former president and call him names.

And after more than a year of uncharacteristic restraint — a notable shift from eight years ago, when his simmering instincts often burdened Hillary Clinton’s first presidential run — Mr. Clinton seems to have had enough.