Just a follow up. This is what inside your LSD.
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As Mark stated, it is based on multiple friction disks (clutch) and not the ‘Torsen’ one.
These disks are soaked in the MTF and as NSX has quite small oil capacity considering its performance and with the ingenious way of circulating the oil for the mechanical parts inside the GBox, the MTF needs to be looked after very well.

Depending on how you drive the car, these disks will eventually wear out and loose the original locking torque. What you experienced was exactly the tendency of standard NSX LSD. The one on Type-R got higher locking setup.

If you have a big socket and torque wrench, you can check the status of your friction disks and understand the torque required to break the locking. You may find it quite low but servicing of LSD requires SST...

Regards,
Kaz