Though each summer seems to come and go in a blink of an eye, the memories and growth that students experience at Summer Stage can last forever. Five years ago, Upper Darby Summer Stage opened its 38th season with the premiere of “The Musical Adventures of Flat Stanley, Jr.  Five years later, past cast members reflect on their experience as “The Musical Adventures of Flat Stanley, Jr.” opens Upper Darby Summer Stage’s 43rd season. Nick Taddeo, who played Stanley in the 2013 production, is eagerly waiting to see his favorite show play again at Summer Stage. Nick is currently studying