Ha, I got that just minutes ago as well. Taught me a lesson for thinking too much about what I was writing.
As mentioned, backspacing usually returns you to your missive. And I always copy my text before so much as clicking "Preview."
But that's nothing compared to this miserable new keyboard that has a button or some easily-fumbled-into key combination that simply closes the browser without asking, and I don't know what it is!
And I just got the darned time-out AGAIN! Once it's tasted blood, there's no stopping it.