That's a bit awkward at the first time. I mean, in Indonesia, we used to kiss older people's hand when we meet them, address them with "Sir" and "Ma'am", bow when we walked in front of them, offer others some food when we eat in front of them, etc.
In America, there's no such thing. You don't now when you walk on front of them. You sometimes called your teacher without any "Sir" and "ma'am" and it's fine. You sometimes don't bother your teacher.
It's not wrong, though. Basically, it's culture. And there's no right or wrong culture, right? It's just... A bit different. And different is good.