Rich Stephens wrote:
When they call an American by his first name plus sensei (as I was called while living in Japan) it is for one of two reasons: either they are mistaken that in English students commonly call their teachers or elders or minor acquantainces by their first name in the states (which is instead rare); or they are just intending to remind you that though they must call you sensei out of surface level politeness, they needn't give you the usual Japanese level of respect because, after all, you aren't Japanese and therefore sensei or not are not above them in society.
I just introduce myself with my last name in Japan (which is what Japanese people normally do) and that's what they use, never had a problem with it. If you introduce yourself with your first name (or even with your first and last names together) then, unsurprisingly, many Japanese people will use it.
Never had problems with Japanese people showing respect in the dojo.
The average language teacher (even Japanese ones) are not in a very high status position, in any case, so I don't imagine that many Japanese would see them as "above them in society".