I got the same recall notice for an Acadia w/ 3.6 L I use to own. It was to reprogram the Oil Life Monitor due to premature timing chain failures.
That tells me two things. The timing chains aren't so great. And, those real long oil change intervals may not be so great if they can contribute to an engine problem.
I never bought into the OLM theory, 3 -5 K changes for me. I've done a ton of oil changes on other peoples cars where they take it down to 0% on the OLM, and that oil looks nasty. I'll trust my eyes before theories, and now there is a recall to back up that suspicion that real long oil change intervals may not be so great - gee who'd of thunk it.