Yeah, there are a multitude of posts on the other forums where silverado guys go through pretty good explanations of what happens when it goes to v4 mode and why lots of highway miles in that mode makes it more likely to be an oil burner after 50k. My suburban started almost exactly at 50k and we are going through the oil burn test right now. On mine, the oil doesn't even register in the dipstick 1500 miles after an oil change.
Fortunately, it is well under warranty and I seem to have a helpful dealership.
For what it's worth, there are also a large number of posts from others with the same 5.3 engine who never had it burn a drop. And, it doesn't appear that the oil burning causes any other problems in the engine.