What time does the day end? Most people would answer that a day ends at midnight. However, a recent GAO decision highlights that, for purposes of filing a pre-award bid protest with the GAO, the business day ends at 5:30 p.m. ET when the GAO closes its doors for the day. Confusingly, this can result in a protest that was technically filed on a Friday after 5:30 p.m. ET, not…