Does Apple have a warranty on their hard drives?
Since you had an Apple authorized service provider for my repair (i.e. the Genius Bar) you now have coverage under two legal agreements.

The original warranty on the machine is still in effect ( or is expired ) but it does not get extended due to the fact that you had a repair. http://www.apple.com/legal/warranty/

The AppleCare terms of service generally offer a 90 day warranty on all parts that runs concurrently with whatever other AppleCare service agreement or original warranty exist. 

Since your repair was a year ago, the 90 days certainly isn't going to cover you and it would be your responsibility to pay for the repair at this point instead of apple's responsibility. http://www.apple.com/legal/sales-support/terms/repair/retailservice.html

The only out would be if you had purchased AppleCare on the original machine and if you were still within the three-year window for coverage. In that case the repaired machine and parts are covered as if they were the original machine and parts.  In that case the repaired machine and parts are covered as if they were the original machine and parts