When you ran nm -A against /usr/sbin/httpd and /usr/sbin/httpd.worker on the RedHat Apache and you get the message :
[root@localhost /opt]# nm -A /usr/sbin/httpd
nm: /usr/sbin/httpd: no symbols
For the Agent to be able to support graceful restart, symbols should be available. That's the only way the Agent can handle the restart.