> What configuration error (technically, by definitions from some IEEE guidelines, mistakes) did they make to have this happening?

They edited .php file on a production server and made a typo, so the file, containing sensitive information started with "i?php" instead of "<?php".

My guess that happened because someone used vi/vim and hit "i" twice.

No. I don't think they do. They've made a mistake and as long as they are willing to take responsibility for the consequences then I don't see the need for a public post-mortem just to satisfy our curiosity.

I guess you're right. Anyway the reason is pretty clear enough after actually reading the pasted code.