My experience
My 2008 Tahoe suffered a failure of the power door lock actuator on the driver's side rear door while under warranty. It would lock every time, but would only unlock maybe once every 5 or 6 times that you tried it. It was repaired under warranty.
About 8 months later, the one on the passenger side back door started doing the same thing. By this time I was beyond the mileage limit of the warranty. I talked to my Service Advisor and made an appointment to bring it in. They replaced the actuator just as they had done on the other side.
After the repair, I asked about the fact that my Tahoe had suffered an identical failure on the driver's side earlier, and was there a problem with the actuators? He asked me if I would like him to cover this repair under warranty as well? I said yes, of course, and there was no charge to me!
This led me to believe that one of two things were at work here. Either he covered it as a courtesy to me as a repeat buyer (I have purchased all my Tahoes from this dealer) or there may be a "hidden" warranty extension on the actuators. I asked him if there had been problems with these actuators, and he just smiled and thanked me for my business.
Perhaps Cadillac Tech can shed some light on this?