I just finished up a P 51 with mechanical retracts. Upon balancing the plane I noticed that with the gear down, it balances slightly nose heavy, but with the gear up, it levels out. Is this acceptable or normal? I balanced it on the Great Planes Balancer upside down according to the instructions at 125mm from leading edge where the wing meets the fuselage. Looks kinda neat hanging there rocking back and forth. Gear down, nose down. Gear up nose level. Do I have a problem or is this normal? First retractable gear.