I try to remember to reboot the servers every month. But sometimes I do get busy and forget. I guess I should write a routine to run under cron to do it automatically, but that's just something else on my TODO list, I guess.
In this case, I don't believe it was caused by simple garbage clogging the server that needed a reboot to clean out. I had a similar problem on this same server just 5 days ago. I'm thinking I need to be looking for a new server host sometime soon. Got the guy who helped me out with that DDoS problem on FaunaClassifieds looking into something for me.