Not uncommon.
It is a visual glitch that does not effect gameplay.
Since it does not effect gameplay it is considered minor and has a low priority for a fix.
It is also most likely due to the devices graphic abilities rather than the app.
Ask support what can be done.
This Forum is provided by EA but is designed as Player helping/advising other Players. In this case there is little other players can do for you.
Contact EA support
http://help.ea.com/en/contact-us/new/ and ask for a gameadvisor. Same login as the game.
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+++ This Forum is provided by EA but it is designed as Player helping/advising other Players - meaning we are not employed by EA +++
D'oh! - Em