That's the thing... I didn't make a reservation and no points were deducted. Plus, the certificate doesn't look like the blue certificate that usually comes with point reservations, it looks just like the Q3FN certificates.
I made a dummy booking for a standard two night points reservation in Category 6, and it gave this reward code:
Reward Code: H602
Description: Category 6 - 2 FREE NIGHTS
So the question remains... what is
PS602?