I can't SEE one on my cassette, but it might be round the other side, or covered by dirt. I think it should be on there somewhere, though, iirc.
But if the seeds of suspicion have been planted in your mind, best to nip it in the bud before the sapling becomes a tree. Send them back, they won't mind. If it is, it probably won't even be parker's fault. They'll just give you a refund, so just get on from a trusted LBS like I did with the SRAM powerlink chain.