Thank you for the TSB information Christen.
This started happening to me last week. It went away for a few days but popped up again last night. Of course my B2B warranty expired 3 weeks ago so I'm sure I'm going to have to pay for this. Hoping my dealer is reasonable since I've read prices from the $335 janny13 mentioned to over $500 on various other message boards. Kind of a lot for an $8 part and less than an hour of work.
I saw in a YouTube video that GM says it should take about 20 minutes to do. Here is the video I found that goes through the fix if anyone is interested in seeing what's involved:
FYI - I also read that there are a few class action law suits for this issue that includes the vehicles listed on the TSB. I guess we'll have to wait and see how they go.