Not a bit, they're far enough back not to. And I never ride with a passenger so that's not a consideration.
I have both lock washers and some rubber "sealing" washers that I'm going to use to keep water from getting into the cans. As a final securing method, I may put wing nuts on the outside of the bolts to keep them from backing out.
You know, I tried to read Zen and the Art of Motorcycle Mainteance and about halfway through I realized that I just didn't care anymore about the whole thing. I think that's one of those books people put on their shelves so they can look "smart" but rarely actually read. I thought it was boring as hell.
BTW same thing happened recently when I tried to read Joseph Heller's WWII Classic "Catch 22." Got 2/3 of the way through it and said "eh, I just don't care about this story anymore" and went back to reading history, which is what I usually read. I just finished Barbara Tuchman's "Stilwell and the American Experience in China" and I'm currently working on "The War that Made America" which is about the Seven Years War A/K/A the French and Indian war from 1754 - 1763. It's written by a CU professor, Fred Anderson.