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Well they're held on there by four screws in the heel, maybe check to see if they're tightened down all the way. If they are and it's just play in the brakes, then I wouldn't really worry too much, the brakes are the most non consequential thing going on back there.
If they ARE loose, bring it to where you got them mounted and have them re-epoxy and perhaps heli-coil if it needs it. There should be SOME play in the heel of an FKS though, as in the heel turntable should be able to rotate.
Hope it's nothing!