It could have been damaged during manufacturing. As others have said, the FEL shouldn't drop with the tractor running.
My tractor has the diverter valve for the independent lift, which was installed by the dealer. Despite following the installation manual regarding the routing of the hydraulic lines from the valve, the 3PH lift arm was still able to contact one of the lines when the hitch was fully lowered. This caused the line to crack near the fitting and gave me a hydraulic fluid shower. The line got replaced and we rerouted it so that it couldn't happen again.
At least your leak was under the seat