What does Zone transfer deferred due to quota mean?

[Smith, William E. (Bill), Jr.]

I'm in the process of setting up some new DNS servers.  After starting
up BIND which by itself starts up without any errors, the server fails
to perform a zone transfer from the primary.  When I look at my logs, I
see errors such as this for every zone
02-Feb-2005 12:00:23.589 info: zone jhuapl.edu/IN/internet: zone
transfer deferred due to quota

I've googled this error and searched the list archives but really didn't
find anything.  I've never seen this error before and am at a loss as to
where the problem may lie.  Will provide any further info as
needed/requested

TIA,

- Bill