I'm almost done with the engine maintenance but I see oil in the throttle body

[Fastguy]

As I'm working with the engine on the stand I notice a bit of oil from the throttle body. I wipe it up and there is enough residual that it comes back three times. It's done working it's way out now, but what could have caused this? Pcv? If so, is that the "non return" valve just beside and by the throttle body?

[Bigglezworth]

Normal. At least for all of my rides it's normal. There will always be some oil in the bottom of the intercoolers also. As the charge condenses the oil vapour turns to liquid. Expect to see a nominal teaspoon of oil in the lower intercooler inlets each year. I've always had to wipe some from the throttle body each time I've done a timing belt or any other front end engine service.

[4everRS]

Like Biggs said, normal. The pcv (positive crankcase ventilation) system recirculates back into the intake just before the turbo's. So, oil vapor is flowing through the system.