Down in the Buydig description:
Pentax - smc DAL 18-55mm f/3.5-5.6 Lens for Digital SLRs W/ USA Warranty
MFG Part#: 21547
Which does not seem to be the WR version (part #21880)
Oh, and there's this comment in the description as well:
Definitely not WR as I bought and returned one from them months ago. Lens was noisy as hell.