Earlier this week, CBS and Warner Bros. TV quietly let the media know they're concerned about Charlie Sheen's off-screen antics, leaking out the story that they've tried to shut down Two and a Half Men so Sheen could get help. Today, their discomfort went public as CBS chief Nina Tassler publicly admitted she's worried about the matter. "I have a high level of concern. How could we not? The man is a father; he has a family," Tassler said during a session with journalists at the Eye's portion of the semiannual TV Critics Association press tour. But Tassler also indicated she didn't have the power to simply order Sheen to shape up. "You can't look at it simplistically. Charlie is a professional," she said. "He comes to work. He does his job very well ... On a personal level, I'm very concerned. On a professional level ... the show's a hit." Producer Warner Bros. is technically Sheen's employer (not CBS), and Tassler said she has "tremendous faith" in how the studio is "managing this." No response yet from Sheen's camp.