H05,
I'm glad you're replacing all 32. I'm with Fred on not burning your bridge with the dealer. You can bitch to the dealer about the tire shop and ask them to help you out by replacing the lugs. They will appreciate that you respect their abilities above those of the local tire store.
I’m sure you know that cross-threading occurs when a nut is placed on a lug without the threads lining up correctly (slightly crooked) and then the nut is forced to cut new threads onto the lug (much like a die cuts threads).
It makes no difference whatsoever if the lugs broke because of cross-threading, over-tightening or production error. Your course is the same.
When OEM wheels are replaced with wider wheels (which require greater offset or track), there is greater stress on the CV joint (according to my Hummer service manager). There is also greater stress on the lugs. I have no first-hand knowledge of this stress breaking lugs, but according to the first URL listed below, this does occur.
http://www.off-road.com/chevy/tech/wheel/
http://www.usacomp.com/Offset.htm
http://www.tirerack.com/wheels/tech/offset.jsp