I did that just last night! On my current project, I sew one area with the needle to the right and another area on the same project with the needle on the left. I forgot and stitched a right area on the left. I thought it looked a little too wide. HA! I have a stickie on my machine that tells me my right/left needle settings for 1/4" seams. I think I need to add another stickie that says CHECK YOUR SETTING!
We're not getting old, were just so artistic and creative and eager to work on our projects that sometimes we have an "ooops, forgot about that".