+3  A: 

Do your files have any spacing or indentation? That could cause your regex not to work.

Your regex will match this

<?

But it won't match any of these because of the spacing.

<? 
 <?
    <?

If you want a regex that allows for spaces and indents try this

^\s*<\?\s*$
Rob
that found them all, thanks!
Edward Tanguay