Mac OS/iPhone clients won't use lease for ~90 seconds

[Apu]

The dhcpd.conf is at http://pastebin.com/m3053e533

The only recent change is to change our 10.12.x.x subnet to a shared
network (10.12.x.x for known clients and 10.112.x.x for unknown
clients).  From the dhcpd logs, I see a fairly normal "conversation"
between server and client and it looks like the client accepts the lease
and should start using it.

Sep 11 12:27:58 ip dhcpd: DHCPDISCOVER from 00:1e:c2:71:dc:dd via 10.12.2.2

Sep 11 12:27:59 ip dhcpd: DHCPOFFER on 10.112.101.176 to
00:1e:c2:71:dc:dd (Perlas-iPod) via 10.12.2.2

Sep 11 12:28:04 ip dhcpd: DHCPDISCOVER from 00:1e:c2:71:dc:dd
(Perlas-iPod) via 10.12.2.2

Sep 11 12:28:04 ip dhcpd: DHCPOFFER on 10.112.101.176 to
00:1e:c2:71:dc:dd (Perlas-iPod) via 10.12.2.2

Sep 11 12:28:05 ip dhcpd: DHCPREQUEST for 10.112.101.176 (10.13.2.2)
from 00:1e:c2:71:dc:dd (Perlas-iPod) via 10.12.2.2

Sep 11 12:28:05 ip dhcpd: DHCPACK on 10.112.101.176 to 00:1e:c2:71:dc:dd
(Perlas-iPod) via 10.12.2.2


But, unknown Mac OS X or iPhone/iPod users in this network have to wait
about 90 seconds for their machines to actually start using the lease
given to them.  Known systems, Windows systems, and Blackberry devices
don't seem to have this delay.

Does anyone see something obvious I'm missing here?

Thanks in advance,


-- 
Apu <apu at pingry.k12.nj.us>
The Pingry School
Martinsville & Short Hills, NJ
http://www.pingry.k12.nj.us/