On the SitePoint PHP blog there's a new post with an interesting question for PHP developers that might go against how they were tought to code from their early days - should you close your PHP tags at the end of your code?
Even those with a modest grasp of PHP know that code must be enclosed within special tags. [...] However, if your file contains just PHP - and no escaped HTML code - the closing ?> tag is entirely optional. Many developers argue that unnecessary code should be removed but there's another reason you could consider scrapping the closing tag.
Their rationale is that, in some situations, extra characters or other information could pop up after that closing PHP tag and cause problems in your code. If you drop the closing tag completely, there's no risk that this could happen and PHP parses it the same way.
There's lots of great comments with opinions both for and against.