Oh yes... How true this is!
Writers write anywhere. Including in their head. Plotting, planning, penning airborne phrases. At any given notice. While eating dinner, walking, or most frequently - in the middle of talking to other people.
When the Muse beckons, we must follow.
Please forgive us. We don't mean to be rude! It's just an occupational quirk. And not a passive daydreamy escapism, but an active working one. Which can yield the best kind of results!