I'm having the same issue with that noise you describe. I have spoken to dealer and showed them at the 1500km service. They agreed it wasn't normal and said they need the car back for a day to pull it apart. They weren't worried about safety or anything. I just need to find time to take it back in.Steering Rack changed uner warranty. But this hasn't changed my issue.
Its not until car gets warm that it makes the noise which is a creaking sound through the steering which can only be heared at low speed and when you go over uneven road or speed bumps. Can be heared when turning in to drive way.
Hyundai Dealer said it been a fault on all i30Ns which I can't really see as it would have been mentioned on here by now.