That sould be covered under your warranty. I just rolled over 40k on mine so im now in my GMPP and i just had the similar work done. I took mine to the local chevy dealership which has a hummer certified tech to do the work as my closest hummer dealership is significantly futher from my house. They changed out my stearing gear box, pitman and idler arms all of which covered under GMPP. Keep in mind i am also running 20's(MarineHawk.....20's can wheel just as well as 17's
), my rock sliders are scraped up and its very visible that i have wheeled this truck when it is on a lift.
On the same note, the dealer had to take my truck down the road to get the alignment done(also covered under warranty when replacing steering gear box/pitman arm) as my truck does not fit on their rack. The facility performing my alignment is well respected as having the best equipement in a 60-90mile radius. Apparently they cannot center my steering wheel perfect because my alignment would not be correct--reason being my frame is pretty well knocked up from wheeling. This was portrayed to the dealership and still no problem. I say bs on the part of the dealer--Old Hiker is right!