Should an '04 Chevy Blazer (automatic) hold a hill when you let off the brake ?

(Reposted from different category due to no responses.)

Should a 2004 Chevy Blazer (automatic) hold a hill when you let off the brake ?
As said, it's an '04 Blazer, automatic, part-time 4 wheel drive, Vortec V-6 engine, and if I let off the brake on an incline it drifts back.

It's still covered under my dealer's 3 month / 3000 mile drive train warranty. If you feel that it should hold on a hill, do you feel that this should be covered under my warranty?

I asked this question previously and wasn't satisfied with the answers, but Yahoo is 999-erroring me if I try to post the link to that question.

Basically I'm asking two questions here:
(1) Do you feel it should hold a hill?
(2) If you feel that it should hold a hill, do you believe that this should be covered under my warranty?

Please try to answer in full sentences, as I'm looking for more than a 'yes-or-no' answer ;-)

Thanks.