Foam fell from metal roof

Hi,

When snow melt this spring, I found a strip of foam right under my roof in a pile of snow where it slides down usually. Immediately, I thought it came from the metal roofing. It's a somewhat new roof (3 years old) with metal shingles, so I called my contractor. He came to see the foam bit and told me it couldn't come from the roof and it must have been blown in from a neighbour by the snow remover. I don't believe it because that pile of snow was on the first step of my front staircase... it would mean that the snow remover blew snow straight into my flowerbed, shrubs and on the house itself. It's just impossible.

I thought about climbing up to find where it was coming from but I have a very steep slope and I don't have proper equipment to walk up there.

Can someone tell me where he thinks it is coming from and if I should care about it or not? (problem leading to possible leaks in the future?)

Thank you very much!