Frost marks on bonnet - new A4 Avant

[gill_a4]

Hi, with the cold nights I've noticed some rectangle and square shapes highlighted by frost on the bonnet in the morning. Looking at the lining on the underneath of the bonnet, it relates to the indented shapes in that. I've never seen anything like it before, and just wanted to see if anyone else has, and if people think that it's just to do with differing levels of insulation making parts colder and so allowing more ice to accumulate, or whether it is something else (what?).
I've attached a few photos showing the frost shapes and the underneath of the bonnet.

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[Gazwould]

Same problem here mate , found out it was extraterrestrials .

[gill_a4]

Ah, crop circles ;-)
Not convinced!

[cuke2u]

In other words its normal for an aluminium bonnet..

[gill_a4]

Thanks.