A couple of questions had to plague the audiences lucky enough to catch Cynthia Rider's stunner of a performance this past spring as the over-nerved, undersexed wife of a vicar in "Bed Among the Lentils," the funniest and most aching monologue in Alan Bennett's Talking Heads. First: Where has Rider been? Years had passed since she had performed before a paying crowd, and her turn as Susan — flattened out, bone-weary, confessing her secrets with a wryness pickled in years of closed-mouth dissatisfaction — was as pained as it was hilarious, as affecting as it was cutting, and always tenderly, believably human. "Once upon a time, I had my life planned out," her Susan said, without sigh or apology, just speaking hard-won truth in Bennett's well-chosen words. Which brings us to the second question that audiences had to be considering: Why do we seem to get such extraordinary words, stories, lives and performances only from the tiny Kansas City Actors Theatre?