I'm not seeing it now, but in the past, I most definitely did. Just make sure your Google verification file is still on the server. A search for that error message on site:google.com shows that it does happen to sites as a bug, but it also can be a real issue with the site. Google's Webmaster Help group might be a good place to go if the issue doesn't resolve soon.
I had to reverify a couple of my sites on a server when they upgraded to latest version of Apache. I had to use the meta tag method though. For some reason it was giving Google a 403 Forbidden response for the .txt file. If you have access to your raw data log check to see if your server is returning a 200 code for your verification file.