One slave notified... other ignored?!?

[Stephen Amadei]

Hey guys.

Recently, I tossed out our old 2 server (slave/master) 8.xxx DNS setup
and replaced it with a 3 server (master/2 slaves) 9.2.2rc1 DNS setup.

For the most part, everything is running fine... but one slave updates
quickly (via a NOTIFY) and one slave updates slowly... via expired
resfresh.  I upped the debug logging and it seems the master is simply not
notifying one slave.  How exactly does BIND learn who it's slaves are?

I read they come from the zone file... which lists...

amadei.com.		IN NS	ns.dandy.net.
amadei.com.		IN NS	ns2.dandy.net.

ns.dandy.net and ns2.dandy.net are both the slaves... the master
has nothing configured on it to make it believe it is ns.dandy.net.
It notifies ns2, but not ns.

What am I missing here?  I suppose I can fix this with a also-notify
in the config, but I want to understand why.  Is it possibly a bug that
BIND assumes it is ns.dandy.net and doesn't sent the notify?

					----Steve
Stephen Amadei
Dandy.NET!  CTO
Atlantic City, NJ