I have always been able to escape and live in my own little world. I have done the same sort of thing, too - forgotten to pick up food at the drive-thru window, or get the cash back that I had requested at the grocery store, then had to return to get it. I always thought it was because I have ADHD, but maybe it is part of my dissociation. I can escape into my own head, go anywhere, become anyone, just sort of float away. Is it like that for you?