Please answer a question about the following article about Washington University in St. Louis:

Washington University has been selected by the Commission on Presidential Debates to host more presidential and vice-presidential debates than any other institution in history. United States presidential election debates were held at the Washington University Athletic Complex in 1992, 2000, 2004, and 2016. A presidential debate was planned to occur in 1996, but owing to scheduling difficulties between the candidates, the debate was canceled. The university hosted the only 2008 vice presidential debate, between Republican Sarah Palin and Democrat Joe Biden, on October 2, 2008, also at the Washington University Athletic Complex.

When was the only vice presidential debate held at Washington University?
October 2, 2008