I've seen this before, some time ago. As I recall, it was usually when SSL connections are timing out and before the server was catching it (IE the connection drops rather than the server closing it).
I also don't have that many SSL users to notice it with, just when servers have split.
Someone else can probably elaborate on the message in more (better) detail, with relation to the IRCd.
As far as I know it can pretty much be the same as a "reset by peer" or similar, where the IRCd just hadn't noticed, and tried to poll the socket for any data waiting to be read.