I feel neurotic when I'm publishing new music. For a day or two before and after I hit the final "submit" button, I'm preoccupied with worries that I need to polish it more, or I missed some glaring technical flaw, or the music just doesn't say anything emotionally. Within a week, I've generally moved on to the next project, the recently published music gets mentally grouped with everything else I've released, and I can return to a state of general optimism about all the music I have yet to write.
I remember a visual artist I knew back in high school expressing a related sentiment...people would offer to buy her work, but she usually couldn't bring herself to sell it, because she never felt finished, and she didn't want to give up the chance to keep working on anything.
Lately, I've shifted to releasing single songs rather than albums, and that seems to help a bit...it's easier to be confident about an artistic judgement call when you've only had to focus your attention on four or five minutes of music, rather than forty-five. Still, it's not my favorite part of the process.