But I wouldn't call the harmless bugs "superficial nitpicks". Most of them could become problems later -- if other code changes result in the functions they are in being called with different parameters; or if an error is no longer treated as fatal but instead Tarsnap continues and retries the failed operation; or with more aggressive compiler optimizations.
Better to fix the bugs before they cause problems than to wait for them to cause problems.
The fact that it satisfied my OCD is just a side benefit. ;-)