Hello Travis,
Could we need more memory, or could it be a network issue? Does memcached have any commands to tell how much of the allocated memory it is using, or are there any other diagnostics I can run to shed light on the issue?
If you're running any older 1.2 release, go upgrade to 1.2.6 or so. Of course, you can just restart memcached and wait for it to happen again :)