It will .... give it time
They definitely distort (and don't leave it in your car on a hot day or lean rod and reel near a radiator) .... some of them also go like a bag of spanners prematurely and they have shite mouldings out of the box.
This is a mag3 but the couple of mag4s I've seen hadn't shown much improvement ...
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The casting comment is daft .... they are about the same size spool with the same size bearings, same spindle setup and same mag system. There will be nothing between them so long as they are running okay.