My girlfriend moves shit around constantly.  You get used to say, the knife sharpener being where it has been for the last 2 years and then she suddenly decides it now is going to live in the 3rd drawer down.  This can happen with any item in the house, I regularly curse her when she isn't there after discovering she has moved some essential item I use.  I am unsure if this her her way of being passive aggressive or she genuinely has some other psychological compulsion she is fulfilling.