I shoot left-handed and my scopes always look canted, whether from a bench or prone. I used to think that they were in fact canted. What is weird though is if I peer thru the scope right-handed, it looks perfectly level. After shooting F-Open, my mind is so captivated by the target, wind, heat-waves etc..etc.. that I do not notice it when I shoot. As far as I know, when I am in "concentration mode" on the target, it may not even appear canted! Your mind can cause or undo an "optical illusion"... However, this is MY story and may not have anything to do with what you're seeing!