The San Diego Chargers re-signed cornerback Dante Hughes and cut cornerback Simeon Castille. Hughes was signed last week and then cut over the weekend as Castille was signed from the practice squad to the active roster for Sunday’s game in Kansas City. Hughes was a third-round draft choice of the Indianapolis Colts in 2007. Source: National Football Post
He was cut because Cromartie got hurt in practice so they brought in Castille as insurance at CB (we would of been down to 2 CBs if Cromartie couldn't go). Hughes doesn't really have the speed for CB (from what I've read). So I'm not surprised they brought him back now that it looks like Cromartie will be ok.