Roger Clemens has Rickey Henderson thinking comeback. “Seeing Roger come back, all the seed that it plants is, ‘Ask me to come back one time,’” the 48-year-old former A’s star said in the New York Mets’ clubhouse before taking on the Giants. “I’m going to look at it at the end of the year. I might come out with some crazy stuff, a press conference telling every club, ‘Put me on the field with your best player and see if I come out of it.’ If I can’t do it, I’ll call it quits at the end.” Henderson is a special instructor for the Mets.