[jolmg]

I guess it's a habit from using the left Shift (and left Ctrl) a lot more frequently than the "A". If I just used the keyboard for writing text, perhaps resting on "A" would make more sense for me.

[gmfawcett]

Nothing wrong with that! Some of us were indoctrinated to rest our hands in a certain way, no matter what kind of typing we do. :)