I updated to build 7191 and the problem hasn’t happened again.
To clarify, I understand the server gone away issue. I haven’t seen this in my logs in a while, but I have seen them in the past. It happens and it has nothing to do with SPF. I get that. However, in every other instance that I have ever seen, there is 1 or maybe 2 entries in the error log, because it was a problem that, no pun intended, went away. In other words, the mySQL server had a glitch, but it came back, and the site continued to operate normally.
In the error I was reporting, SPF was filling the log, something that I have never, ever observed before. I suspect that the cause of filling the error log was the ticket that Andy mentioned above when discussing “clean up the code”.
If Andy’s fix wasn’t in build 7191, maybe there was something else going on. Maybe I had a bad download. But to have SPF generating a 100 Mb error log on 1 instance of “server gone away” isn’t the way things should be, so I’m glad it’s not doing that anymore 🙂