Country music star Waylon Jennings was "doing just fine" after 31/2 hours of triple bypass heart surgery, a hospital spokeswoman in Nashville, Tenn., said."There was no evidence of a heart attack," Bridget Dolan, the Baptist Hospital spokeswoman, added after Monday's operation. The 51-year-old singer, who had an angioplasty in October, was hospitalized Sunday morning after having chest pains while traveling to a concert in Bristol, she said. Jennings' wife, singer Jessie Colter, and son were with him at the hospital, and the entertainer was in good spirits before surgery, Dolan said.