ipv6 network aliases not set after upgrade to 9.3

Greetings all:

I have a host that recently was upgraded from FreeBSD 9.1
to FreeBSD 9.3.  After the upgrade, the IPv6 aliases that
I was setting on vlan'd interfaces, no longer get set:

The section of my /etc/rc.conf, which worked under 9.1:

# inside network (gigabit connected)
ifconfig_bce1="up"
vlans_bce1="16 17"
ifconfig_bce1_16="192.168.16.4/24"
ifconfig_bce1_16_ipv6="inet6 accept_rtadv"
ifconfig_bce1_16_alias0="inet6 2001:470:e254:0010::4 prefixlen 64 alias"
ifconfig_bce1_17="192.168.17.4/24"
ifconfig_bce1_17_ipv6="inet6 accept_rtadv"
ifconfig_bce1_17_alias0="inet6 2001:470:e254:0011::4 prefixlen 64 alias"

When I use the same configuration file under 9.3, I get the
vlan'd interfaces created, and they get an auto-assigned
IPv6 interface, but the aliases do not get assigned.

If I manually run:

ifconfig bce1.16 inet6 2001:470:e254:0010::4 prefixlen 64 alias
ifconfig bce1.17 inet6 2001:470:e254:0011::4 prefixlen 64 alias

Then the aliased addresses get assigned.  Did the syntax for
specifying aliases on vlan'd interfaces change subtly for 9.3 vs 9.1?

I did not see anything calling out this change in either the 9.2 or 9.3
release notes.

Thanks!

-Kurt