If you're in the middle of typing something and then you put the phone aside for a bit, it will refresh the tab when you come back to it and everything will be annihilated.
I'm not sure if this happens with the editor, since both times for me it was a forum post, but I suspect it works the same way.
If it's a mobile only problem it probably can't be fixed, but just posting this as a heads up for anyone doing anything more serious with the RTE.
(It's really too bad because the RTE would otherwise be perfect for flash fiction on the forum now that it has the word count....)
I think this probably happens RTE or no RTE!