Madts:

I’ve done this several times… I’m not thinking, pickup the sander (an expensive Mirka, no less), and ‘sanded’ for a few minutes before realizing what I’ve done. I agree with both Brian and a1jim.
Having said this, I’m very careful about who I let use my powertools and equipment. The simple fact is that woodworking is dangerous – Life can come at you fast.
Mike