As a left-handed person, I can definitely confirm I've encountered handedness bias plenty of times in my life.
Just like with other "defaults" in things like race and sexual orientation, right-handed people typically don't think of themselves as having a certain handedness until it's explicitly pointed out.
Try being a paperclip collector for a day...
I just read a blog post on NeuroLogica Blog that could have been a LW post, so I figured that I would bring it on over. It basically details how knowing about our biases can help us correct for them, a la the lens that sees its flaws, and then brings to light a new study (unfortunately behind a paywall... I wanted to see the methodology) that shows that the simple act of wearing a glove on your dominant hand can influence how you perceive the world.
When I learned that Dexter and Sinister were Latin words for Right and Left, respectively, I was told that it came from shield formations, and how the person on your left was a leech for using your shield protection, and the one on your right was your protector. Now that explanation sounds a bit hollow.