News of her illness has resulted in Dunham being "inundated" with phone calls, e-mails and flowers from "total strangers" who are wishing her well, Obama said.
"And so, maybe she is getting a sense of long-deserved recognition toward the end of her life," Obama said.
Ever the presidential candidate, Obama invoked his grandmother when talking about issues in the campaign.
When asked by Roberts about his plans for health care, Obama said, "I think about my grandmother right now. But, you know, there are a lot of younger people who, in her same circumstances, don't end up having health insurance. Sometimes their kids don't have health insurance."
He also dismissed McCain's latest attack that Obama "will say anything to get elected." McCain was referring to Obama's alleged shift in his plan for who would be eligible for tax cuts.
"I think it's fair to say that if you look at the quality of our campaign and theirs," he said, "who's been more civil, who's talked about the issues, as opposed to trying to attack peoples' character, I think we get a pretty good grade."
Grandma, at least, would approve.