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You're right.  It's not quite.  But it did give me the metric I was looking to see if was fixed.  Thanks!

Not currently. You would need to download the CSV each month, and compare via Excel. Not terribly hard to do once you've got a process in place. There are other tools that will do this, some better than others. Raven is the most popular toolset that offers this feature that I am aware of. They're a competitor to SEOMoz, but they also offer Open Site Explorer link data, so I'm assuming it's still in good taste to mention that one on here.