Weird relocation of desktop icons


I have a dual monitor system. Today, I awoke my computer from sleep and somehow all of the icons from the left screen (my main display) ended up on the right screen, while the taskbar remained on the left side. I went into display settings and found that my choice for the main display somehow ended up on the right. I changed it back, but the icons didn't move. I had to move them manually back to the left side. Is there some kind of keyboard shortcut that I could have hit that would have switched these?