Thats not necessarily the case anymore though. In the past they used to release the news soon after they would complete the deal and the contracts would commence either the following month or a couple months later.
But the last news release shows they've changed tact, because the contracts were already underway from January 1st and it was made public January 13th. I bet they signed those contracts sometime in December or November of and then waited for an appropriate time to make the news public.
Its the same case now with the tour buses. I believe they are already up and running or will be by February 1st, and that the company made the deals sometime in 2010 and are waiting for an appropriate time to release the news. Maybe they were/are waiting for some institutions who were using the shorts sells to build a position, maybe a present for the Chinese new year, but most likely IMO they've learned what nicely timed PRs can do for a company and its image as well as building shareholder value.
If they wanted, I bet they could have a new PR every week until earnings, but why use an Ace when things are falling into place on their own.