'sobvious innit ~ you had visitors, she didn't want them to see the vacuum cleaner in case they thought a "special" effort had been made to tidy up for their visit because, like all wimmin, she wants them to believe your house is always clean and tidy ~ so she hid the cleaner where she thought they wouldn't see it. Of course the only person she fooled was herself, until this morning when she set you a little test and then, as we now all know, she fooled you too. Put the cleaner back under the bed and despite the evidence of absent needles etc she will never believe you have cleaned up. Wimmin!
My ex wife did a good line in leaving the cleaner where I would fall over it when I came home ~ then she would claim that she had been soooo busy she had not had time to put it away yet. Truth was she had been swigging coffee with her mates all day. Aonther favourite was to move picturs so that they were hanging crooked on the wall. She knew I would spot this and straighten the picture (can't abide crooked pictures) when she would claim to have dusted all the picture frames that day.
You may like to use these tips at a future date.