I have two parts left after display replacement (iPhone 4S)

I had to replace my iPhone 4S's (64GB, black, bought in Europe) display and I did that by following this great guide: iPhone 4S Screen Replacement

Everything worked fine so far, but after reassembling the device I had this two parts left:

https://www.dropbox.com/sh/kigbfwilvkbbe...

(same images as attached but second image with huge resolution for more details)

Does anybody have any idea where these could come from? In what step I may have missed them? Or even what they could be?

Even after re-reading the guide I have no clue where these parts come from... I think they might have fallen out at some point.

The phone works great without them btw ;)

Thank you very much in advance!

Best,

Michael