The DBAN autonuke feature may also Nuke the Flash Drive (and as usual, any other drive it detects). To prevent DBAN's autonuke feature from wiping the thumb drive, pendrivelinux subscriber Lee Sonko suggests the following:

"Remove your thumb drive after dban has loaded, but before it has started wiping drives."

that means taking the usb drive out after selecting automatic option and "loading ......" on the bottom of the blue screen is finished. take it out right before/when the black screen starts