black crocs arrived with reflective dust – has that happened to you?

Hi, so this might be weird but i ordered some black crocs slides from amazon (UK, sold and dispatched by them) but they arrived covered in this weird reflective substance. I thought it was just part of the plastic at first but it transfers when touched. it's fine strand like bits of dust, not too many but enough to be significant, and I'm kind of worried that it might be fiberglass dust or something, which is a bit worrying as I opened them sitting on my bed(it's not glitter).

I was wondering if anyone here has ever seen something like that and if it might be part of the manufacturing process, maybe.

Thank you :)