I have definitely found the same thing in my 35mm photos. Futher more, I see that when I crop a 6x6 neg to fit on a rectangular paper, it too is usually of a vertical (portrait) orientation.

I almost would like to ask a mean, mean question: to all the RB67 users, if your back was to get jammed in one position - and you could pick, which would it be?

Sorry, thats an evil one - but they have their RB's and I am still saving for mine!