Just lube it yourself and get used to it. You'll have to do it for the life of the car. GM outsources this part to another company that has their heads up their collective ass.
Here are directions:
North American Impala Owners Association - Problems with my car! - ISS Intermediate Steering Shaft Fix Sticky
Keep in mind, this is probably the most common and hardest to beat problem on W-bodies. There are rumors that the latest shaft design is better, but no confirmed reports with a part number. One guy had this problem with only 5 miles on the odometer in his 08 Imp SS.
