I think it is a bug.
Basically the webapp that deploys to http-listener will get loaded before admin listener starts up. The app during its initialization will try to access 4848 and will fail.
When QuickStartup is off, it gives a connection failure error. When QuickStartup is on, since the serversockets will be bound early, the client will wait.
[Message sent by forum member 'binod' (binod)]
http://forums.java.net/jive/thread.jspa?messageID=210023