Happens to me constantly. Our brains are dumb. Ironic. They
   don't know the difference between what we _plan to do_ and what
   we _actually did_ all that well.

   Once we can that "satisfied" feeling [of mentally composing the
   text message], we quickly forget the steps required to make it a
   reality; get the phone, push the fake letters (or say them out
   loud) and we're just left with this satisfied/completed feeling.

   Takes a few weeks to backtrack unconsciously and go, WAAAAIT A
   SECOND..... that was a DREAM... wasn't it? I DIDN'T ACTUALLY
   _DO_ ANYTHING!

   SHIT, not again.