i am definitely of the opinion that you shouldn't be concerned about another persons rank.
In our dojo, rank is only questioned around testing time, to decide what you are going to test for next and who is leading classes.
Correct me if I am wrong, but historically, whether it be chinese wushu, or budo, rank was never an issue. There weren't "ranking systems" the way that there are now. There were white belts and black belts. The "western ranking system" was brought about, because us westerners needed to see smome kind of sign of progression.
I am definitely a novice in martial arts compared to most of you, but I think there is just too much attention put on issues of rank. There are definitely too many ego's out there in different colored belts looking for more "rank" to boost up an inflated ego.
When i train, i take everyones' opinion and experience in to help my waza. In other words, i always try to keep my cup empty.