Suddenly Bank Changed the locks

I have a short sale that has only been listed for 3 months,the seller has only missed 3 payments ans all of the sudden the bank sent someone out to change the locks without notifying the seller or myself and also took my expensive electronic lockbox. The lis pendens was just filed and recorded on August 12th,2009. Is this unusual? Do I have any recourse to get my lockbox back? Just wondering if anyone else has had this issue come up.