As someone who got fired from 1 of my previous jobs because said customer was mocking my height by calling me a "midget," and I stuck up for myself, I too do mind the term. It is offensive, and furthermore, is ableist language.
And, no, the word is NOT thrown around "casually" in US pop culture. Petite is the word used here to describe short people.
Yes, short people are awesome -- Veronica Lake, Kristen Chenoweth, Jessica, and many others - and yes you meant no offense -- but please pick your word choices more carefully next time. Better yet, rather than assuming you know what words are used in US culture to describe short people, use one from your own culture and tell us "this is word we use for people who aren't tall."
I like her dress in the pictures. It's very lowkey, but she's not promoting anything, so it makes sense it's not flashy. But I'm hoping for another red carpet event soon. I love seeing her gown choices!