Further WTF of the better kind...
A reboot fixed the problem, and it seems to be doing the session files somehow, but they are not in the sessions directory. I have no idea what voodoo is at work here. Other weirdness, httpd didn't start at boot. I tried to start it manually and is complained that the server.crt file was missing. I checked and it was there, so I tried again and it started just fine. dmesg reports no disk errors. *very confused*