I bought an item from ebay a month ago, the seller provided me with tracking number and so i waited and tracked for a whole month. Now it has not arrived yet, the tracking says that

Processed through USPS Sort Facility
2012-03-07, 19:11:00, LOS ANGELES, CA 90009

and this is the newest update available since the 7th of march. I contacted the seller but he replied and says that it will arrive soon. Should i start an 'item not received' dispute? Can i file a claim even if the seller provided me with tracking details? The 45 days validity to open a dispute is almost over, please help!