Not worry per se, but I really prefer working on clean parts. Had my fair share of rust encounters early on in life. That's when I started learning how to weld.
Don't like rust, dirt, whatever, anywhere underneath a vehicle, not even on the beaters. My hands should ideally be as clean when I'm done as they were when I started the job.
So for me, getting a new vehicle that will most likely never be driven in rain show up with surface rust would be quite disappointing. I'll probably change oil in the '18 Challenger soon, and then I could take photos from underneath. Except for the discoloration of the exhaust, everything should look just like when I first got it.