PRESS PHOTO BY TIM GILMAN Lehigh University student Alex Sereno and his mother, Stephanie, stop to admire (or smell the) blooming tulips in Bethlehem at the corner of New and Church streets, near City Hall and the public library. The Lehigh junior was spending Easter Sunday with his parents who were visiting from Rhode Island. 'It's beautiful here,' commented Mrs. Sereno while walking around the Bethlehem Historic District on the city's Northside for her first time. Alex noted that he rarely traverses from