Unless the odd time for tyre fitting to loose wheels since the garage does it for free if I buy motorcycle tyres from them when there's a special deal on. (mechanics.stackexchange.com)
I've had car's with LOOSE wheel hub components move and make contact with that shield. (mechanics.stackexchange.com)
One thing you might want to check is your wheel bearings, as damaged or loose wheel bearings can cause a «floating» issue with the front end that tends to clear up when braking... (yourmechanic.com)