Obviously, you do not want to offer the impression that you are not reliable, prepared, and on-time. That said, sometimes an extreme circumstance might arise when you have to execute a plan for the unlikely. If your honest answer to this question is 'yes,' then orient the focus of your answer on the steps you took to mitigate the problem and ensured as smooth and stress-free of a situation as possible. Keep in mind that being late to a wedding can include events leading up to the wedding, itself, such as shots of the wedding party getting ready or the guests filing in.