Thanks! and...grinding while turning

I bought a 2016 Prius Two about three months ago. It has about 27,000 miles on it. Soon after, I found that the fuel filler door wouldn't open. Thanks to this forum, I learned about the tech bulletin about this, and that the spring in the door just needed to be replaced with a bigger spring. So when I took it to the dealer, I sounded intelligent instead of the automotive moron that I actually am.....so please keep that in mind as you read my question:
I recently noticed that when I turn, there's a very faint sort of grinding sound, sort of like the sound it makes when braking. It's so faint that I can only hear it when the motor isn't running. I'm not sure if it's only when I turn left, or both directions. I have heard it when backing up to the left, also. Is this sound normal, or not? My previous car was an '01 Corolla, so I'm still getting used to all the different noises the Prius makes....Thanks very much in advance for any suggestions. It's under warranty, and I'm taking it in for an oil change in a couple weeks so if there is anything wrong, I'll have them look at it then.