Yes, and I was confirming that this is a possibility given the data they pulled. I had also mentioned datalogging as a "need" in these situations, because aside from the visual onceovers, that is part of the modern diagnostic toolbox. Datalogging is easily done with Torque Pro and an OBD adapter. There is a thread on custom parameters in addition to what Torque natively provides for this platform.
Since the dealership has the XSport, maybe then can scope out the intake valves at the same time. Since the XSport is not driven much, and if it is not driven hard on occasion, it is very possible they are coked up. IIRC, BG had said about every 30,000 miles on their treatment to prevent carboning from becoming an issue, and your XSport is sitting in that spot right there.