Sam Shepard went into hiding at Le Cirque when the cast of “August: Osage County” appeared for a Q&A at the restaurant on Wednesday. Spies at producer Jean Doumanian’s lunch reception said that silver fox Shepard attended along with castmates Chris Cooper, Abigail Breslin, Juliette Lewis, Margo Martindale and Julianne Nicholson, but when the rest of the actors began a panel with The Post’s Michael Riedel, Shepard instead “disappeared behind a bar with a glass of champagne and got on his cellphone for an hour.” He refused to drop the seemingly important call even when the other thespians urged him, and offered a full bottle of champagne as a bribe. “He was pretending to talk on the phone,” hypothesized one witness, “while five other cast members begged him [to join them].” Another spy said they overheard the Tony-winner during his lengthy conversation saying into his phone, “Oh, yeah, I had the fish.” During the panel, Lewis defended Shepard’s decision, saying: “Sam is a cowboy. It’s a miracle he’s even here. We should count our blessings.” But once the Q&A ended, shy Shepard rejoined the party to happily schmooze and stay till the bitter end. (Perhaps he was afraid of Riedel’s penetrating questions?) Co-star Julia Roberts is expected at a premiere of the Weinstein Company movie on Thursday, but Meryl Streep is in South Africa filming Weinstein’s “The Giver” with Katie Holmes.