As the landing gear was retracted after take-off, the baggage door warning light illuminated and a noise consistent with a propeller strike was heard. The aircraft returned for a landing on runway 34, and on inspection the nose locker door was found open. A piece of baggage was missing. A bag was found on the runway and there was evidence of propeller slash marks on it. The pilot stated that he had checked the nose locker door prior to starting engines and it was locked. The door may have become unlocked due to baggage pressure on it. The lock has been replaced as a precautionary measure.
