There is no issue here that I see. Here is a brand new install I am doing and you can test it
http://www.reeftalk.com/classifieds/index.php
Go ahead and run sendnotice.php yourself
http://www.reeftalk.com/classifieds/sendnotice.php
It does not expire ads that are not expired period and here is the query in sendnotice.php
// Close out expired ads
$query = "UPDATE {$Globals['pp_db_prefix']}products SET approved=2,status='$today' WHERE enddate < $today AND isauction=0";
$result = ppmysql_query($query,$link);
NOTICE WHERE enddate < $today