I didn't assume, but I can tell right away when someone has English as a second language like you do.

I pick up grammatical oddities as I read, and if I had to guess i'd say your first language is of Asian origin, possibly Filipino.

Of course that doesn't mean you aren't American, but I assume you are not vs are in this kind of situation.

It probably depends on how "American" the forum for discussion is vs global, I see HN more American then say, Reddit.