The government's plan to sell its stake in General Motors Co. throughout the next 12 to 15 months comes with a few surprises.

The buyback came earlier than expected, Jefferies analyst Peter Nesvold said, and the structure of the deal took a different form than he was predicting. But most importantly, GM purchasing 200 million shares of the government's stake at $27.50 a share represents a lower price than he was anticipating.

"While an eventual sell-down was not a surprise, the timing, price, and structure were," he says in a note to client. "We were expecting something at least $30."

GM's share repurchase of the stock held by the Treasury Department marks the first step of the government's eventual exit from the auto maker within the next 12 to 15 months. The deal represented a 7.9% premium from Tuesday's closing price and will reduce the Treasury's stake in GM to 19% from 26.5%.

Many analysts have said the government's stake in the automaker has weighed on GM shares in the past. But that mindset appears to have become less of an issue. "We think this perceived overhang has been easing over the past year, and perhaps even flipped to being seen as a prospective catalyst as investors looked to own more GM ahead of the company's product cycle, an improving housing cycle and early signs of a European restructuring plan," Nesvold says.