Mike,
Yes this is a known problem with all GM vehicles (mainly the suvs) It has been around for as long as they have been putting plastic door handle buckets in.
I thief takes a flat head screw driver, jams it in and breaks the plastic on the bottom right side, fumbles around with the screw driver and eventually finds the little lever behind the door bucket and then the door unlocks.
It is a pathetic flaw in the deisgn of GM vehicles and is sad that they havent done anything to fix it. It causes a lot of problems, and typically even messes up your paint around the door handle when a thief does it.
There are 3 fixes I know of...
Replace the plastic door buckets with metal door buckets
Buy this little contraption that mounts behind the door bucket and prevents tampering with the door lock assembly (jimmyjammer I think it is called)
or Cut the door unlock lever and totally disable key access to that door
http://trucktechniques.com/jimmijammer.html