For one, the 30 second execution time can be changed using [man]set_time_limit/man, but that doesn't apply in this situation; the PHP script isn't even executed until the client has finished uploading the file.
EDIT: Perhaps I was mistaken. Either way, you could increase the max_execution_time and max_input_time directives as described in this article just to be sure.
EDIT2: Ah, found the reference in the manual ([man]file-upload.common-pitfalls[/man]):
PHP Manual wrote:Note: max_execution_time only affects the execution time of the script itself. Any time spent on activity that happens outside the execution of the script such as system calls using system(), the sleep() function, database queries, time taken by the file upload process, etc. is not included when determining the maximum time that the script has been running.
Thus you only should worry about directives such as max_input_time, post_max_size, upload_max_filesize, etc.