August 30, 2012 No Comments FREE Sub at Firehouse Subs on Labor Day Enjoy a FREE medium sub on Labor Day when you purchase any sub combo. Valid at participating Firehouse Subs with printed offer on 9/3/12 only. Locations. FREE Sub at Firehouse Subs on Labor Day -EXPIRED Facebook Twitter Add Comment Notify me of follow-up comments by email. Notify me of new posts by email.