There's nothing in your language use so far that would have tipped anybody off that you're ESL
Thanks for the praise. Coming from a fellow writer makes it ever so pleasing.
About the ESL - I work as an editor for several sites, as a part time gig. Majority of writers are ESL, much like me. But, they originate from Pakistan, India and other Middle/Far Eastern countries. While i am not the one to judge, I think it has something to do with the English program they have in schools. Most of them use antiquated words, some of which became obsolete about 120 years ago, others struggle with syntax and use of adjectives.
I think they regard their English skills to be excellent, which is probably true, by Eastern standards. In US/UK they are not however, and that could be the reason why they are so defensive.