Presidential nominee Hillary Clinton spoke at the Democratic National Convention Thursday evening, but one very small line in her speech caught the attention of a Republican official.

"It comes down to what Donald Trump doesn't get: America is great — because America is good," Hillary Clinton said in her DNC nomination acceptance speech.

It's the "America is great — because America is good" part.

Sean Spicer, who works for the Republican National Committee, tweeted that Clinton lifted the phrase from political scientist Alexis de Tocqueville.

Who's that? He was a 19th century French aristocrat who wrote "Democracy in America." De Tocqueville is credited with the phrase, "America is great because she is good."

Here's what's interesting: That line isn't anywhere in de Tocqueville's book.

Instead, a Weekly Standard article from 1995 says the line appears to have first been used in a book on religion 75 years ago.

The author attributed the phrase to de Tocqueville's book, but as the article notes, "The author may have mistaken his own notes for a verbatim quotation, a common problem in the days before photocopiers."

Still, it's a phrase long been used by U.S. presidents, including Dwight D. Eisenhower, Ronald Reagan and even Bill Clinton.

It's one of a few times the word "plagiarism" has been used at this year's political conventions.

Last week, the person who wrote Melania Trump's RNC speech admitted she unknowingly used quotes from Michelle Obama's DNC speech in 2008.

And just this Thursday, Donald Trump Jr. tweeted that he was "honored that [President Obama] would plagiarize a line" from Trump Jr.'s speech at the RNC.