Unfortunately, information can often be slow to update. This is results from a variety of reasons. Essentially, Trulia relies on updates from both real estate agents as well as MLS data. If information from either of these sources is incorrect... well, bad data in equals bad data out.
The best way to obtain up to the minute information about properties is to work directly with an agent who is actually engaged in the market (many realtors do real estate part-time). An active real estate agent will have more accurate information about homes that just hit the mls (homes that would take a few days to show up on Trulia or any other national real estate sites) as well as homes that have not hit the market yet.
I hope this helps!