This one was annoying - I've got a nice old bayes database that apparently the spamassassin was having some trouble with from time to time. Thankfully a little searching found the answer:
spamassassin, bayes and berkeley db
I also had a bunch of bayes_toks.expire#### files, I think its OK to just delete those... looking now.... not sure. I did it anyway, will keep an eye on the logs just in case.