What was found
THE RT MLG RED UNSAFE LIGHT REMAINED ILLUMINATED AFTER GEAR RETRACTION LEAVING IAH. WHEN OFF POSITION WAS SELECTED, BOTH RED AND GREEN LIGHTS WERE ILLUMINATED. THE AIRCRAFT WAS RETURNED TO IAH WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE ADJUSTED THE RT MLG UPLOCK SENSOR TARGET. A RETRACTION TEST WAS PERFORMED AND ALL INDICATIONS CHECKED NORMAL.