Strange Sound my 08' is making

Yesterday, just had regular maintenance done, oil, brakes checked, fluids etc as well wheels rotated.
After holding your breath fingers crossed in hopes all is good, I had the dealer tell me my rear brakes are at a "3", and need replaced, well I use Les Schwab for my tires and brakes, and took my car to the for rotation and shown them what the dealer said on my reciept.
Well the manager came out to tell me my brakes are fine, they are not as bad as was told to me.
So I trust them finish up and on my way.
I noticed a weird rubbing on metal sound , words are hard to explain this. But it reminded me of a sound that an emergency brake would make when in reverse backing up you forgot to release.
But that isnt the case it happens while driving at speed limit and it sounds spontaneously. But isnt a good sound. Since Prius really dont make much sound at all. Its a metal on metal sound rubbing sound.

Any ideas, help to this before I drag my child back for a recheck will win smarty of the year! Please and thank you!

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Guess what the pancake it was? My license plate cover was rubbing on the grill that is low on the front end and rattling. Les Schwab found the noise!

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Thats what i was thinking. But ut was the license plate cover in the front end. Blahhh

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