You say that but I cannot find it anywhere in the FAQ.
https://www.ddo.com/forums/showthrea...-Purchase-FAQs
If I don’t pre-purchase the expansion, can I still buy the pre-purchase items at a later time?
The following item colors will not be available in the DDO Store after the pre-purchase period ends on June 24th 2012, nor will they appear in future expansion bundles:
Demonweb Spiderling Creature Companion
Druid’s Wolf Pup Creature Companion
Onyx Panther Cub Creature Companion
Notice how it doesn't even say panther hireling or the spider mask.
I've read a lot of past MotU threads, and still have not come across a post from a DDO employee stating that the panther hireling is exclusive.