As root, I ran sa-learn on my spam corpus from the /root directory, and I got a msg when it finished like the one below only a different number. Then I ran the same sa-learn command, although from the /root/spamassassin directory (bayes_path), and this time it completed without the "lock" msg. It learned all but 4 of the >400 msgs, and I have the expected bayes_ files in the bayes_path directory.
Then I ran sa-learn on my ham corpus. Again I got a "lock msg". I ran the same command again, and got the lock msg again: Learned from 0 message(s) (244 messages examined). unlock: 8791 unlink failed: /var/spamassassin/bayes.lock # /var/spamassassin does not have a bayes.lock file at this time, but does have bayes_seen and bayes_toks from the --spam learn session. Earlier today I tried using the -D option, but the debug output never finished, and I eventually finally had to control-C out. Anyone know what causes this bayes.lock msg??