Ashley, of course it shouldn't have an effect if mirror is applied, but shouldn't the mirror remain afterwards when you extend it? I realize the process is mathematically correct but the wording on "flipped” state and "mirrored” state indicates that once you apply it, it should behave as it is flipped/mirrored.
It's a small matter, I'd probably never benefit from it, was just interested in getting it to be more intuitive maybe.
Thanks anyway!