Arianna Huffington’s surprise gift to Jon Stewart -- a convoy of shuttle buses to his “Rally to Restore Sanity” in Washington -- was an even bigger surprise to the folks at the Huffington Post. And the cost of the grand gesture -- an estimated $250,000 for 100 buses for thousands of New Yorkers -- is making some of Huffington Post’s finance executives wince, according to insiders. HuffPo’s President Greg Coleman agreed that the gesture came a surprise, but denied that there was any internal tension as a result.