No clue. It's either DW, your FTP tool, or your web host. It seems too randomly placed to be the latter two and I can't imagine why they would be adding code in anyway.
If it's a pure basic HTML file with all of the coding on that one page, then I'm not sure why even DW would add code to the file. If the page is generated dynamically, I could see where it might be harder to track down the issue.
Do you hand code your stuff, or do you use the WYSIWYG editor at all? I could at least see using the WYSIWYG aspect and somehow DW shows one piece of code but then something gets converted when you publish it to the web. If you are using the WYSIWYG editor, you might want to redo that part and double check what you are doing.