CKEditor 3.3 all grey - no text entry field

Hi,
I've been using FCKEditor and CKEditor for quite a while on my Drupal website, but recently I've come across a silly problem where I suspect that CKEditor is choking on a little piece of PHP code that I've got embedded in my text field. On the two pages where I use this piece of code, CKEditor now opens all grey, with no text entry field.


As I said, i suspect it's got something to do with a little piece of PHP code that has been there in the text for a long time, but suddenly (version 3.3?) causes a problem.
The piece of code is used to calculate (and thus automatically present) my age on homepage and Resume.

<p>
   Hi, my name is .... and I am <?php 
function getAge( $p_strDate ) {
    list($Y,$m,$d) = explode("-",$p_strDate);
    return( date("md") < $m.$d ? date("Y")-$Y-1 : date("Y")-$Y ); }
echo getAge("1967-08-20"); ?> years of age and .....</p>

Has anyone else run into something like this?
Stephan