We do not understand how it is already Labor Day weekend. Where did the summer go? You’ve still got a few weeks to wring all you can out of the last days of summer, starting with the Blue Hill Fair, which runs through Monday at the beautiful Blue Hill Fairgrounds. There are two concerts at the Maine Savings Amphitheater in Bangor this weekend: country artist Walker Hayes on Friday, and hair metal icons Bret Michaels, Warrant, Dee Snider and Firehouse on Sunday. And all weekend at the Augusta Civic Center, there’s the annual Maine’s Odd and Unusual Show, featuring hundreds of vendors selling everything from jewelry and home decor to taxidermy and bone crafts.