Hi all, I just got my brand new Nikon AF-S NIKKOR 18-35mm f/3.5-4.5G ED for my D750 and after few minutes of usage I noticed a strange mechanical sound when zooming from 24mm to 28mm. The lens seems to work properly (for now), does anybody has the same sound? Should I be worried or it's normal? I found a post of a guy that experienced after few months a similar noise (can't be sure it's the same, mine is very low) and he sent the lens back to service. Just wondering if I should do the same. It's really really really disappointing that you get a not-so-cheap lens from Nikon and have to send it back already after 2 minutes! Please let me know if this is something I should be worried about or not, thanks!!!