Maren Morris is impressed…The Oak Ridge Boys are feeling Christmas already… Maren Morris's "Girl" became her second number-one single this week, after “I Could Use A Love Song,” and her fastest-rising single to date. She considered “Girl” a leap of faith.She said, "When we put this song out as a single, you know, it's very rock, so I didn't know how it was going to fare at radio, but I just believed in it so much. So,…