Texas concertgoers were treated to a special surprise when Grammy Award-winning singer-songwriter Lisa Loeb took the stage to perform the mega-hit “Keep On Loving You” with REO Speedwagon at the band’s “Live & UnZoomed” summer tour at Dos Equis Pavilion in Dallas on Sat., July 23. This isn’t the first-time the Loeb has performed the song, however. She has …