JUST SAY NO?

During last night's performance, a little voice in my head said, "You're auditioning. Somebody in the audience is watching you." And I thought, "Boy, I have a vivid imagination. I wish." So in the lobby after the show, the director of a new show called "Witchcraze" approached me about auditioning for her show. She explained that she had been watching me during the show, liked my singing and stage presence, and wanted me to audition. It was flattering (and a little odd, since I had the premonition, or whatever it was). But I don't want to be in the show, and I feel awkward, because I'm not that great at saying no. It's not socially acceptable to say, "I don't want to." Everyone expects you to say, "I'd love to, but..." Why do I have to come up with a lame excuse?