PID file ... not readable after restarting zabbix-agent.

Observation:
Does not occur when rebooting the system.

To reproduce:
1. Execute "sudo systemctl ]restart | stop ] zabbix-agent ", then start.
2. Observe error message with "sudo systemctl status zabbix-agent "

978|[[email protected] ~]$ sudo systemctl status zabbix-agent
? zabbix-agent.service - Zabbix Agent
Loaded: loaded (/usr/lib/systemd/system/zabbix-agent.service; enabled; vendor preset: disabled)
Active: active (running) since Wed 2016-06-01 11:17:50 EDT; 1min 43s ago
Process: 1013 ExecStart=/usr/sbin/zabbix_agentd -c $CONFFILE (code=exited, status=0/SUCCESS)
Main PID: 1088 (zabbix_agentd)
CGroup: /system.slice/zabbix-agent.service
??1088 /usr/sbin/zabbix_agentd -c /etc/zabbix/zabbix_agentd.conf
??1102 /usr/sbin/zabbix_agentd: collector [idle 1 sec]
??1103 /usr/sbin/zabbix_agentd: listener #1 [waiting for connection]
??1104 /usr/sbin/zabbix_agentd: listener #2 [waiting for connection]
??1105 /usr/sbin/zabbix_agentd: listener #3 [waiting for connection]
??1106 /usr/sbin/zabbix_agentd: active checks #1 [idle 1 sec]

Jun 01 11:17:49 example.com systemd[1]: Starting Zabbix Agent...
Jun 01 11:17:50 example.com systemd[1]: Started Zabbix Agent.

981|[[email protected] ~]$ ls -ltr /var/run/zabbix/
total 4
rw-rw-r-. 1 zabbix zabbix 4 Jun 1 11:17 zabbix_agentd.pid

983|[[email protected] ~]$ sudo systemctl stop zabbix-agent
985|[[email protected] ~]$ ps aux|grep -i za[b]
986|[[email protected] ~]$ sudo systemctl start zabbix-agent
987|[[email protected] ~]$ sudo systemctl status zabbix-agent
? zabbix-agent.service - Zabbix Agent
Loaded: loaded (/usr/lib/systemd/system/zabbix-agent.service; enabled; vendor preset: disabled)
Active: active (running) since Wed 2016-06-01 11:20:13 EDT; 5s ago
Process: 2847 ExecStart=/usr/sbin/zabbix_agentd -c $CONFFILE (code=exited, status=0/SUCCESS)
Main PID: 2849 (zabbix_agentd)
CGroup: /system.slice/zabbix-agent.service
??2849 /usr/sbin/zabbix_agentd -c /etc/zabbix/zabbix_agentd.conf
??2850 /usr/sbin/zabbix_agentd: collector [idle 1 sec]
??2851 /usr/sbin/zabbix_agentd: listener #1 [waiting for connection]
??2852 /usr/sbin/zabbix_agentd: listener #2 [waiting for connection]
??2853 /usr/sbin/zabbix_agentd: listener #3 [waiting for connection]
??2854 /usr/sbin/zabbix_agentd: active checks #1 [idle 1 sec]

Jun 01 11:20:13 example.com systemd[1]: Starting Zabbix Agent...
Jun 01 11:20:13 example.com systemd[1]: PID file /run/zabbix/zabbix_agentd.pid not readable (yet?) after start.
Jun 01 11:20:13 example.com systemd[1]: Started Zabbix Agent.