Going against the grain isnt mindless at all and certainly not sheep like, its called independent thinking.
Going against the grain is neither automatically mindless nor automatically intelligent. If you do it without thinking, which was what you indicated, that is - by definition - mindless.
What you describe isn't independent thinking at all, it's completely dependant upon what everyone else does, and no thinking is involved.
People who think for themselves will at least sometimes do what the mainstream does because they don't care and may not even know what the mainstream is doing.