Only as a witness to a traffic accident. My point is this was a publiahed article. The folks who prepped him should have anticipated hostile questions based on published critical articles. He should not have answered "no" if he wasn't prepared to claim his accuser was lying. Under the circumstances, the best answer would have been the full truth, followed by a "so, what's your point?" He isn't getting the nomination anyway -- never was -- so why wimp around?
BTW, when I take depositions of people, it is not expected that they are going to have perfect memories about things, particularly things that come out of left field like this question did. Simply put, when you are questioned under oath it is not supposed to be a memory test and any good judge understands that. But by your standards, I could turn everyone I have ever taken a deposition of into a liar by getting them into a memory test about what happened to them 10 or 15 years ago.