Yes, I have experienced that. I just started taking a medication about a month ago and when that began to work I think I realized that I almost always had at least a little depression going on in the background...something always telling me "yeah, but what about this, don't forget that" - something to remind me of the bad stuff. Then as I began to feel better, any time a difficult moment came along I panicked a little inside worried that it was just a lucky little passing moment and the slide back into the usual crummy mood was coming back. That thought began to depress me, too. It's a vicous cycle, so I'm sure there are lots of us who can understand that feeling you're having. Hang in there, and hopefully it will just pass on by!