Remove node from Load Balance not very graceful

We brought our new datacenter online this week with everything behind a pair of 1500D firewalls. The websites are setup with the Fortigate's performing the load balancing functionality.

Today our developers needed to deploy an update and asked us to take a node out of the loop. Our network guy logged into the Fortigate, went to the Load Balance Monitor, and under the heading Graceful Stop/Start, clicked stopped for the node in question. To our surprise, pending sessions to that web server were suddenly dropped.

To me, a graceful stop on a load balancer would stop sending new sessions to that node and let pending sessions wrap up. There is nothing graceful about the stop.

Is there some setting I missed?

Denny