I highly doubt it. PHP is processed on the server side before any output to the client is generated.
Perhaps the hacker is looking for .phps (php source), .txt or other files assuming you have stored an alternate copy of the file with a different extension...
Also, check to make sure that you have hidden .inc files (if you use the .inc extension for includes). Unless you specify explicitely in apache to hide files with the .inc extension, it will simply show those files as text files.
-sridhar
P.S. Perhaps the hacker is exploiting an apache exploit?? or maybe it's not a hacker at all!