Yeah, nancy_smith is probably right about tired brains, but stuff like this happens to me all the time. It feels like there's a weird gremlin that just moves one thing a day.
Except it's not always about being tired... I've had days where I'm wide awake and still put my keys in the fridge. Lisa's gremlin idea is closer for me. Sometimes the brain just glitches on simple stuff, no reason needed.