Sotheby's As a Predictor of the World Economy

There is an interesting article in The Atlantic about how the art  market and in particular Sotheby's is a useful predictor of the world economy. The reasoning is that over investment, overconfidence and easy money  drive up the price of auction house bids.

"In May 2010, an anonymous bidder believed to be Chinese forked over $106 million for Nude, Green Leaves, and Bust, the most ever paid for a Picasso. Five months later, three bottles of Chateau Lafite 1869 sold at Sotheby's for 30-times their pre-auction estimate, at $230,000 per bottle to Chinese bidders. In November, an 18th century vase sold for $70 million. Eight figures for a vase."

Is the Sotheby's indicator pointing to a bubble in China?