I should probably read all posts prior to replying, but I'm afraid I'll forget.
I, too, have noticed that while drafting a pm, I had the RETURN button shift the entire line on which I'd just typed DOWN a line. It was as if I'd hit 'HOME' prior to return...but at the time I was working on a mac, which requires a completely different, 2-key combination to accomplish that, so I'm certain after duplicating the problem it's the text editor.
I did not have this issue in the sandbox.
I am having this same problem, also if I hit the backspace button too quickly, it backs up lines instead of letters...it happened while I was creating my "My Chickens" page too...