Vlad,
I ran across this each time I use the "Move selected line" shortcut (which is a very handy feature), after I use it and don't follow up with anything else (such as entering a new line or other text modifications) when I leave that note and come back the line I just moved will have moved back to were it was. Funny, for a while before I discovered that this was a bug I thought I had forgotten to move the line, moved it again each time and thought my short term memory was failing :-)
I then tried moving several lines around instead of just one, as long as there isn't a text modification such a carriage return, everything will revert back if the page is left and subsequently returned to. When you are able, please look at this.
Thank you,
Bryan