LAB:
It was on the left side of the bike when I bought it as well. I asked if it mattered and was told that t would make no difference, so I moved it.
I put it on the throttle side thinking that if I ever needed to adjust it on the fly, I'd just pull in the clutch and reach for it with my throttle hand. It's the same reason I've got my reserve gas tap on that side.
Never actually don't either "on the fly" so I don't know if my theory hold water, but there it is.