During its "Cleanup" phase, Time Machine has recently been deleting backups from several months ago—even though these aren't the oldest backups, and my backup drive isn't full.
My backups go back to January 2012, yet just today, Time Machine deleted backups from May 21, June 11, July 2, and July 23 (all in 2012). And plus, my Time Machine drive still has 200 GB free.
Why's it doing this? Shouldn't it just either delete my backups from January 2012 first (if it needs the space), or just delete the expired backups in the past 24 hours or 30 days (based on its normal rules)?