After a segfault of HTTPD for reasons similar to the situation described in KB 128431, the watchdog hasn't detected the server being down and has not done any restart reattempt or send an alert.
consider to investigate your issue/problem with the help of "strace" ... for example:
First, please stop watchdog and apache completely and then restart apache with the command "strace -ff -o /var/log/test_trace.log -r apachectl start". Try several gracefull restarts ( and reloads ) and restart watchdog afterwards as well to investigate any issues/problems at your temporary log "/var/log/test_trace.log". If you need help with your investigations, please post the temporary log and include as well your apache2 modules, please.
Additional manual for "strace" for CentOS 7 ( the commands don't vary for CentOS 6 or 5! ) : http://www.unix.com/man-page/centos/1/strace/( External link, please inform me if this link is dead, so I can provide another helpfull link! )