I do this when driving all the time. I drove a whole road length once and just like..realized that I was on the highway without remember driving there.
i definitely know how this feels. all of my friends are so spread out across creation that sometimes it feels like i've spent the weekend driving. and more than a few times i've zoned out on the parkway or turnpike and i come to my senses as i pull into the my driveway and i'm like: i don't remember one second of the last 45 minites. but DANG do i sleep well after one of those zone-out dealies.