As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAH - FL 1840, IMMEDIATELY AFTER GEAR RETRACTION, THE AFT CARGO DOOR LIGHT ILLUMINATED. AIRCRAFT PRESSURIZED OK. FLIGHT RETURNED TO FIELD AT IAH. DURING GEAR EXTENSION, LIGHT WENT OUT. FLIGHT LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE REMOVED AND REPLACED THE AFT CARGO DOOR PROXIMITY SWITCH. OPERATIONAL CHECK GOOD. (M)