Estas são as razões dadas em docs do MySQL:
The max_allowed_packet variable value is too small or queries require more memory than you have allocated for mysqld. See Section C.5.2.10, “Packet too large”.
Use of Ethernet protocol with Linux, both half and full duplex. Many Linux Ethernet drivers have this bug. You should test for this bug by transferring a huge file using FTP between the client and server machines. If a transfer goes in burst-pause-burst-pause mode, you are experiencing a Linux duplex syndrome. Switch the duplex mode for both your network card and hub/switch to either full duplex or to half duplex and test the results to determine the best setting.
A problem with the thread library that causes interrupts on reads.
Badly configured TCP/IP.
Faulty Ethernets, hubs, switches, cables, and so forth. This can be diagnosed properly only by replacing hardware.
E, this explica melhor:
Although they could be a symptom of a larger problem, they can be caused from normal (i.e. unpreventable) network issues.
Even if they're on the same LAN, for a variety of reasons, communication errors may occur between your application server and the database. In the cases of corrupt communications or time-outs, the applications and/or MySQL most likely retries and works and the problem never surfaces or makes itself apparent.
In my experience, the most common sources of these types of messages are from the application (server) flaking out, the application not terminating connections properly, or from latencies in off-site replication.
Quite likely they were happening before you enabled error logging on the MySQL server.