Well depending on the severity, it can be normal. On every car, doesn't matter what manufacturer, paint on the plastic bumpers and side skirts will never 100% match paint on the metal body parts. Paint on 2 different surface types won't match completely, only manufacturers are able to do is get as close as possible without it being remotely noticeable. You mainly see it in direct full sunlight. Should be covered under warranty if it really bothers you.
__________________
|2013 Audi S4|Ibis White/Black|S-Tronic P+|
|2013 370z|PearlWhite/Persimmon|Touring/Sport/Nav|F.I. CBE 18" CF|
|Sold|2011 370z|Gun Metallic|Touring/Sport/Nav|
|