The heartbeats may be missing. And once 3 heartbeats missing in the CTIOS server it is expected to cycle to re-establish the connection between CTIOS and CTIserver. This is a self cycling mechanism to keep CTIOS going. Cycling of CTIOS will not have any effects on agent login, or call drop.
Try to increase the heartbeat Interval to 15 sec. This will prevent CTIOS from recycling, if any slowness in Inter process communication has delayed the heartbeat events from being propagated to CTIOS server.