filters are lost after a while

Hello, I got an issue with php-apc. I'm using debian packaged version, both 3.1.3p1-2 (squeeze stable) and 3.1.9-0.1~bpo60+1 (squeeze backports). Both version have the issue. my apc.ini is : extension=apc.so apc.shm_size=64M apc.ttl=3600 apc.filters="+\.class\.php$","-.*/blog\.conf\.php$","-.*/templates_c/.*","-.*/cache/.*" for a few hours, all is working fine, it does the job well, caching the files I want and not caching the filtered files. But after a while (it's very random, can be a few minutes or several hours), it start caching filtered files. If I watch the apc.php stats files, listing the cached files, I see : *hidden*/blog.conf.php and several others files in templates_c and cache directory. I do not know what others informations I can provide to help you understand what's going on, so just ask ! :) Thanks Florent.