I got the same message, even though I personally only downloaded a dozen or so torrents.
However the last couple of days when I search/browse for torrents, random torrents will be highlighted in green and/or as downloaded. These torrents I did not download, in fact most of them I hadn't even looked at.
I thought this was just a visual glitch/bug, but if the system actually thinks I downloaded all these torrents, I can understand why it would warn me I'm almost reaching the limit.