Andy Pettitte decided to pitch for the New York Yankees in 2008 and put off retirement. Pettitte’s agent, Randy Hendricks, said Monday that the 35-year-old left-hander had started telling teammates on Sunday. Hendricks then informed Yankees general manager Brian Cashman of the news. Hendricks said Yankees captain Derek Jeter and catcher Jorge Posada had lobbied Pettitte to return, and the pitcher…