failed multi-view zone transfer

[jeffreyp]

greetings,

i'm in the midst of an odd problem (to me, anyway) and would appreciate 
any pointers.

three servers, all running bind-9.7.2-P3 compiled from source with the 
same options.  one master; two slaves.  two views:  internal and 
external.  one master and one slave are on the same subnet with just a 
switch between 'em; the other slave is on a different subnet "out on the 
internet".

i'm wanting to have both views for all zones transferred to both slaves. 
  i've set things up with tsig and per mark andrews' great scheme 
documented at 
http://www.mail-archive.com/bind-users@lists.isc.org/msg03593.html

transfers from the master to the slave on its same subnet happen as 
desired; transfers from the master to the slave on the different subnet 
do not.

notify logging shows that the notifies are being properly received by 
both slaves.

my master zone definitions specify also-notify for both slaves.  each 
slave zone definition specifies a masters statement.

what i've observed (initially because of a typo and quite by chance) is 
that the transfer to the slave on the internet does not happen if the 
host specified in the SOA's MNAME field is also specified in an NS record.

but if the host specified in the SOA's MNAME field is not an NS record 
then the transfer does complete.  and therein lies the problem.

i've intentionally not posted my config, thinking someone might 
recognize this off the top of their head.  i will certainly post it if 
necessary.

thanks,

jeffreyp