Barrels coming apart?

I just got my old Belgian double back from my smith that did some lockup and bore work on the gun and test fired it with what he believed to be hot handloads he bought at a gun show (real smart right?). All of the work he did looks great and he did a fine job but now I can hear debris rattling down the barrel when I flip the gun up and down. What is this? Will it get worse? Do I need to have the barrels re-soldered?