Got the vouchers on the HKG-SFO flight back home on Jan 12th.
Would be in HKG again for couple days this Sept. May drop by to see if they still give out the same gift.
The PJ given out on our return leg, the S size remains the heavier grey color material same as the one on our inbound flight in December while the M size has changed to a dark color that I could not describe what it is, and of lighter material.