For a brief moment, “^DS” signaled a new day. After years of obstructive communication, the Washington Area Metropolitan Transit Authority had finally hired a dedicated public relations official who appeared transparent, competent, and enthusiastic about his job. Dan Stessel was warmly received by Twitter’s legion of Metro-haters, signing his tweets with his initials, and he seemed to engender a little bit of love for a beleaguered transit system. But as 2011 winds down, Stessel’s presence has become less and less noticeable. He no longer issues rapid-fire responses to inquiries. Tweets of Metro alerts once again come with little detail. The agency proved itself capable of letting in sunlight, but perhaps sustainability was too much to expect.