New to CGC, question about my shipment and appearance 0

[Derek Marconi]

Hello, 

  I have purchased several CGC graded comics in the past from different sources. I sent my first shipment to CGC of 10 comics recently, and when I received it, there appears to be an oily reflective substance in the case. It is rainbow like and reflective like oil. Is this because they are newly pressed, or is this an issue I should be bringing up. I have had other collectors mention to me it looks odd. Please advise, is this normal? Will it fade, or do I need to ask for them to be re cased? 

Thanks for reading.

[The Lions Den]

Google "Newton Rings" and I think you'll find the answer...there are whole threads dedicated to this phenomenon... 

[Jeffro.]

Or check out this link for more info

https://the-comic-book-forum.boards.net/thread/1277/causes-newton-rings-simple-explanation