Apparently we’re at the point in Campaign 2012 where we play the game of dissecting political statements for “gotcha moments.” The pols have to be ready for the questions, so they should work to make sure they mitigate damage by reading up beforehand. That being said, of all the things to talk to a Presidential candidate about, why focus on interpretations of who exactly was a Founding Father? But, since it was broached….
The question, from ABC’s George Stephanopoulos, and Bachmann’s answer:

Stephanopoulos: [E]arlier this year you said that the Founding Fathers who wrote the Constitution and the Declaration of Independence worked tirelessly to end slavery. Now with respect Congresswoman, that’s just not true. Many of them including Jefferson and Washington were actually slave holders and slavery didn’t end until the Civil War….
Bachmann: Well if you look at one of our Founding Fathers, John Quincy Adams, that’s absolutely true. He was a very young boy when he was with his father serving essentially as his father’s secretary. He tirelessly worked throughout his life to make sure that we did in fact one day eradicate slavery….
Stephanopoulos: He wasn’t one of the Founding Fathers – he was a president, he was a Secretary of State, he was a member of Congress, you’re right he did work to end slavery decades later. But so you are standing by this comment that the Founding Fathers worked tirelessly to end slavery?
Bachmann: Well, John Quincy Adams most certainly was a part of the Revolutionary War era. He was a young boy but he was actively involved.

First of all, because “some” Founders had slaves doesn’t mean that “some” didn’t fight against slavery. This isn’t an “either or” kinda thing. Besides, someone else offered an opinion on this (H/t)

Who were our fathers that framed the Constitution? I suppose the “thirty-nine” who signed the original instrument may be fairly called our fathers who framed that part of the present Government. It is almost exactly true to say they framed it, and it is altogether true to say they fairly represented the opinion and sentiment of the whole nation at that time. Their names, being familiar to nearly all, and accessible to quite all, need not now be repeated….
In 1784, three years before the Constitution – the United States then owning the Northwestern Territory, and no other, the Congress of the Confederation had before them the question of prohibiting slavery in that Territory; and four of the “thirty-nine” who afterward framed the Constitution, were in that Congress, and voted on that question. Of these, Roger Sherman, Thomas Mifflin, and Hugh Williamson voted for the prohibition…[t]he other of the four – James M’Henry – voted against the prohibition, showing that, for some cause, he thought it improper to vote for it.
In 1787, still before the Constitution, but while the Convention was in session framing it, and while the Northwestern Territory still was the only territory owned by the United States, the same question of prohibiting slavery in the territory again came before the Congress of the Confederation; and two more of the “thirty-nine” who afterward signed the Constitution, were in that Congress, and voted on the question. They were William Blount and William Few; and they both voted for the prohibition…This time the prohibition became a law, being part of what is now well known as the Ordinance of ’87….
In 1789, by the first Congress which sat under the Constitution, an act was passed to enforce the Ordinance of ’87, including the prohibition of slavery in the Northwestern Territory. The bill for this act was reported by one of the “thirty-nine,” Thomas Fitzsimmons, then a member of the House of Representatives from Pennsylvania. It went through all its stages without a word of opposition, and finally passed both branches without yeas and nays, which is equivalent to a unanimous passage. In this Congress there were sixteen of the thirty-nine fathers who framed the original Constitution. They were John Langdon, Nicholas Gilman, Wm. S. Johnson, Roger Sherman, Robert Morris, Thos. Fitzsimmons, William Few, Abraham Baldwin, Rufus King, William Paterson, George Clymer, Richard Bassett, George Read, Pierce Butler, Daniel Carroll, James Madison.

Thanks for clearing that up, Mr. Lincoln.
Is this a stretch? Perhaps, but no more, really, than the gymnastics that Stephanopoulos went through just to get to this point.