I think it's a North American Aviation thing... The wheel well covers on the P-51 are the same way, remaining closed when the gear is down (until the hydraulic pressure bleeds off enough to let them fall open. As soon as the engine starts, they zip back up again).. In fact, both the Mustang and B-25 doors can get "out of sync" and close while the gear's retracting, but before the wheels get up in the wells... All the pilot can do keep cycling the gear until they "get right", and stay open until the gear is full-up..