Plus trulia and sites like it aren't updated instantly, depending on how the listing information is entered into trullia, sometimes it can take a bit of time to get updated if done by a database upload, rss delivery feed or other method, hand entered listings are updated the fastest.
If really interested in finding out the exact reason why even further, check trulia's instructions and information for brokers on data uploads.
A new trend in my area is that agents are stating in the description that they are waiting for approval of a satisfactory offer or only taking backup offers and this helps improve my productivity in the market and keep my clients happy by not wasting time.
