AFter deciding to go to GD today for an evo grind and velium pelt collection, I chose to camp the Bloodmaw ph's and surrounding mobs. After 20-30 kills, it became obvious that these ph's (frosted kodiak) are not dropping pelts, and are still dropping the occasional Feather. I haven't killed enough of the non ph kodiaks yet to determine if they are dropping the pelts or not. Conversely, I have seen wurms in GD and instances dropping pelts since the patch.
I have to eat my words, on exactly the 32nd kodiak kill, I got a velium infused pelt to drop. That still seems a bit rare, but RNG is as RNG does.