I completely understand, I'm the same way with my cars! It really doesn't make sense that the dealer and the new owner would both miss something so big. I just don't think the spoiler produces enough down force to pull up rocks from the ground and cause damage. It might be true but I'm trying to...
I agree! Very odd but that could be the case. I'm still not convinced it hasn't been happening on a transport truck though. These cars are (supposed to be) loaded back-first when transported to dealers.
I think you're on the right track with your plan now. Don't worry about what happened since new (your car still has low miles) and start tracking any oil consumption now.
Personally I'd do an oil change to ensure myself it has the correct 5W-50 weight oil. Otherwise get out there and drive!